Life

(Greek zoe; Latin vita; French La vie, German Das Leben; vital
principle; Greek psyche; Latin anima, vis vitalis, German
leberzskraft).

The enigma of life is still one of the two or three most difficult
problems that face both scientist and philosopher, and
notwithstanding the progress of knowledge during the past twenty-
three hundred years we do not seem to have advanced appreciably
beyond the position of Aristotle in regard to the main issue. What
are its characteristic manifestations? What are its chief forms?
What is the inner nature of the source of vital activity? How has
life arisen? Such are among the chief questions which present
themselves with regard to this subject.

I. HISTORY

A. Greek Period

The early Greek philosophers for the most part looked on movement
as the most essential characteristic of life, different schools
advocating different material elements as the ultimate principle
of life. For Democritus and most of the Atomists it was a sort of
subtle fire. For Diogenes it was a form of air. Hippo derives it
from water. Others compound it of all the elements, whilst some of
the Pythagoreans explain it as a harmony -- foreshadowing modern
mechanical theories. Aristotle caustically remarks that all the
elements except earth had obtained a vote. With him genuine
scientific and philosophic treatment of the subject begins, and
the position to which he advanced it is among the finest evidences
of both his encyclopedic knowledge and his metaphysical genius.
His chief discussions of the topic are to be found in his peri
psyches and peri zo�n geneseos.

For Aristotle the chief universal phenomena of life are nutrition,
growth, and decay. Movement or change in the widest sense is
characteristic of all life but plants are incapable of local
movement. This follows on desire, which is the outcome of
sensation. Sentiency is the differentia which constitutes the
second grade of life -- that of the animal kingdom. The highest
kind of life is mind or reason, exerting itself in thought or
rational activity. This last properly belongs to man. There are
not in man three really distinct souls, as Plato taught. Instead,
the highest or rational soul contains eminently or virtually in
itself the lower animal or vegetative faculties. But what is the
nature of the inner reality from which vital activity issues? Is
it one of the material elements? Or is it a harmony the resultant
of the balance of bodily forces and tendencies? No. The solution
for Aristotle is to be found in his fundamental philosophical
analysis of all sensible being into the two ultimate principles,
matter and form. Prime Matter (materia prima) is the common
passive potential element in all sensible substances; form is the
determining factor. It actualizes and perfects the potential
element. Neither prime matter nor any corporeal form can exist
apart from each other. They are called substantial principles
because combined they result in a being; but they are incomplete
beings in themselves, incapable of existing alone. To the form is
due the specific nature of the being with its activities and
properties. It is the principle also of unity. (See FORM; MATTER.)
For Aristotle, in the case of living natural bodies the vital
principle, psyche is the form. His doctrine is embodied in his
famous definition: psyche estin entekexeia e prote somatos fysikou
dynamei zoen exontos. (De Anima, II, i), i. e. the soul is
therefore the first entelechy (substantial form or perfect
actualization) of a natural or organized body potentially
possessing life. The definition applies to plants, animals, and
man. The human soul, however, endowed with rationality is of a
higher grade. It is form of the body which it animates, not in
virtue of its rationality but through the vegetative and sentient
faculties which it also possesses. The union of these two
principles is of the most intimate character, resulting in one
individual being. The form or entelechy, is therefore not a
substance possessed of a distinct being from that of the body; nor
in the case of animals and plants is it a reality separable from
the body. The human soul, however, seems to be of a different kind
(genos etepron), and separable as the eternal from the perishable.
Aristotle's conception of the soul differs fundamentally from that
of Plato for whom the vital principle is related to the body only
as the pilot to the ship; who moreover distinguishes three
numerically different souls in the individual man.

B. Medieval Period

The Aristotelian theory in its essential features was adopted by
Albertus Magnus and St. Thomas, and the doctrine of the vital
principle as form of the body prevailed supreme throughout the
Middle Ages. The differences separating the rational soul from the
vital principle of the plant or animal, and the relations between
intellectual activity and sensory cognition became more clearly
defined. The human soul was conceived as a spiritual substantial
principle containing virtually the lower faculties of sensory and
vegetative life. It is through this lower organic capacity that it
is enabled to inform and animate the matter of the body. But the
human soul always remains a substance capable of subsisting of
itself apart from the body, although the operations of its lower
faculties would then necessarily be suspended. Because of its
intrinsic substantial union with the material of the organism, the
two principles result in one substantial being. But since it is a
spiritual being retaining spiritual activities, intrinsically
independent of the body, it is, as St. Thomas says, non totaliter
immersa, not entirely submerged in matter, as are the actuating
forms of the animal and the plant.

Moreover, the vital principle is the only substantial form of the
individual being. It determines the specific nature of the living
being, and by the same act constitutes the prime matter with which
it is immediately and intrinsically united a living organized
body. The Scotist School differed somewhat from this, teaching
that antecedently to its union with the vital principle the
organism is actuated by a certain subordinate forma corporeitatis.
They conceived this form or collection of forms, however, as
incomplete and requiring completion by the principle of life. This
conception of inferior forms, though not easy to reconcile with
the substantial unity of the human being, has never been
theologically condemned, and has found favour with some modern
Scholastic writers, as being helpful to explain certain biological
phenomena.

With respect to the question of the origin of life Aristotle,
followed by Albertus Magnus, St. Thomas, and the Schoolmen
generally, believed in the spontaneous generation even of
organisms comparatively high in the animal kingdom (see BIOGENESIS
The corruption of animal and vegetable matter seemed to result in
the spontaneous generation of worms and insects, and it was
universally assumed that the earth under the influence of moisture
and the sun's heat could produce many forms of plant and animal
life. St. Augustine taught in the fifth century that many minute
animals were not formally created on the sixth day, but only
potentially in a seminal condition in certain Portions of matter -
- and subsequently several Catholic philosophers and theologians
admitted this view as a probable theory (cf. Summa I:59:2;
I:71:1). However, the concurrent agency of a higher cause working
in nature was assumed as anecessary factor by all Christian
thinkers.

C. Modern Period

In respect to the nature of life as in regard to so many other
questions, Descartes (1596 1650) inaugurated a movement against
the teaching of Aristotle and the Scholastics which, reinforced by
the progress of science and other influences, has during the past
two centuries and a half commanded at times considerable support
among both philosophers and scientists. For Descartes there are
but two agents in the universe -- matter and mind. Matter is
extension; mind is thought. There is no possibility of interaction
between them. All changes in bodies have to be explained
mechanically. Vital processes such as "digestion of food,
pulsations of heart, nutrition, and growth, follow as naturally
from dispositions of the organism as the movements of a watch ".
Plants and animals are merely ingeniously constructed machines.
Animals, in fact are merely automata. In the "Traite de l'homme"
(1664), he applied the language of cogs and pulleys also to human
physiology. Thus muscular movement was explained as due to the
discharge of "animal spirits" from the brain ventricles through
the nerves into the muscles, the latter being thereby filled out
as a glove when one blows into it. This tendency to regard the
organism as a machine was also fostered by the rapid advances made
in physics and chemistry during the eighteenth century and the
earlier part of the nineteenth, as well as by the progress in
anatomical research of the Italian schools, and even by the
discoveries of such men as Harvey, Malpighi, and Bishop Stensen.
The earlier crude mechanical conceptions were, however, constantly
met by criticism from men like Stahl. If the advance of science
seemed to explain some problems, it also showed that life-
phenomena were not so simple as had been supposed. Thus Lyonet's
work on the goat-moth revealed such a microscopic complexity that
it was at first received with incredulity.

Stahl (1660-1734) himself advocated an exaggerated form of
vitalism. Rejecting the mechanical theories of the Cartesian
School, he taught that life has its source in a vital force which
is identical with the rational soul in man. It is conceived as
constructor of the body, exerting and directing the vital
processes in a subconscious but instinctively intelligent manner
by what he calls logos in contrast with logismos, whilst it rather
inhabits than informs the body. Others separated the vital force
from the sentient soul and adopted "didynamism". Notwithstanding
the growth of materialism, vitalism achieved considerable success
during the second half of the eighteenth century. It was, however,
mostly of a vague and inconsistent character tinged with Cartesian
dualism. The entity by which the organic processes were regulated
was generally conceived as a tertium quid between soul and body,
or as an ensemble of the vital forces in antagonism and conflict
with those of inanimate matter. This was substantially the view
held by the Montpellier school (e. g. Barthez, Berard, Lordat) and
by Bichat. Even to men like Cuvier life was simply a tourbillon, a
vortex, a peculiar kind of chemical gyroscope. The Bildungstrieb
or nisus formativus of Blumenbach (1752-1840), who judiciously
profited by the work of his predecessors, exhibits an improvement
-- but succeeding vitalists still showed the same want of
philosophic grasp and scientific precision. Even a physiologist of
the rank of Claude Bernard was constantly wavering between une
idee creatrice -- whatever that may mean -- and une sorte de force
legislative mais nullement executive, and the mechanical organism
of Descartes. Von Baer, Treviranus, and J. Muller favoured a mild
kind of vitalism. Lotze here, as in his general philosophy,
manifests a twofold tendency to teleological idealism and to
mechanical realism. The latter, however, seems to prevail in his
view as to the nature of vegetative life. The second and third
quarters of the nineteenth century witnessed a strong anti-
vitalist reaction: a materialistic metaphysic succeeded the
idealistic Identitatsphilosophie. Even the crude matter-and-motion
theories of Moleschott, Vogt, and Buchner gained a wide vogue in
Germany, whilst Tyndall and Huxley represented popular science
philosophy in England and enjoyed considerable success in America.

The advent of Darwinism too, turned men's minds to "phylogeny",
and biologists were busy establishing genetic relationships and
tracing back the infinite variety of living types to the lowly
root of the genealogical tree. To such men life was little better
than the movements of a complicated congeries of atoms evolved
from some sort of primitive protoplasmic nebula. The continuous
rapid advance both of physics and chemistry flattered the hope
that a complete "explanation" of vital processes was at hand. The
successful syntheses of organic chemistry and the establishment of
the law of the conservation of energy in the first half of the
nineteenth century were proclaimed as the final triumph of
mechanism. Ludwig, Helmholtz, Huxley, Hackel, and others brought
out new and improved editions of the seventeenth-century machine
view of life. All physiology was reduced to processes of
filtration, osmosis, and diffusion, plus chemical reactions. But
with the further advance of biological research, especially from
about the third quarter of the last century, there began to find
expression among many investigators an increasing conviction that
though physico-chemistry might shed light on sundry stages and
operations of vital processes, it always left an irreducible
factor unexplained. Phenomena like the healing of a wound and even
regular functions like the behaviour of a secreting cell, or the
ventilating of the lungs, when closely studied, did not after all
prove so completely amenable to physical treatment. But the
insufficiency of physico-chemistry became especially apparent in a
new and most promising branch of biological research --
experimental morphology, or as one of its most distinguished
founders, W. Roux, has called it, Entwicklungsmechanik. The
embryological problem of individualistic development had not been
adequately studied by the older vitalists -- the microscope had
not reached anything like its present perfection -- and this was
one main cause of their failure. The premature success of the
evolution theory too, had led to a blind, unquestioning faith in
"heredity", "variation", and ' natural selection" as the final
solvents of all difficulties, and the full significance had not
yet been realized of what Wilson styles "the key to all ultimate
biological problems" -- the lesson of the cell. Recent
investigation in this field and better knowledge of morphogenesis
have revealed new features of life which have conduced much
towards a widespread neovitalistic reaction.

Among the chief of these has been the increased proof of the
doctrine of epigenesis. Already in the eighteenth century
embryologists were sharply divided as to the development of the
individual organism. According to the advocates of preformation or
predelineation, the growth of the embryo was merely the expansion
or evolution of a miniature organism. This theory was held by
ovulists like Swammerdam, Malpighi, Bonnet, and Spallanzani, and
by animalculists like Leeuwenhoek, Hartsoeker, and Leibniz. In
this view the future organism pre-existed in the primitive germ-
ovum or spermatazoon, as the flower in the bud. Development is a
mere"unfolding", analogous to the unrolling of a compressed
pocket-handkerchief. Though not quite so crude as these early
notions, the views of men like Weismann are really reducible to
preformation. Indeed the logical outcome of all such theories is
the "encasement" of all succeeding generations within the first
germ-cell of the race. The opposite doctrine of "epigenesis",
viz., that the development of the embryo is real successive
production of visible manifoldness, real construction of new
parts, goes back to Aristotle. It was upheld by Harvey, Stahl,
Buffon, and Blumenbach. It was also advocated by the distinguished
Douai priest, J. Turberville Needham (171-1781), who achieved
distinction in so many branches of science. In its modern form O.
Hertwig and Driesch have been amongst its most distinguished
defenders. With some limitations J. Reinke may also be classed
with the same school, though his system of "dominants" is not easy
to reconcile with unity of form in the living being and leaves him
what Driesch styles a "problematic vitalist". The modern theory of
epigenesis, however, in the form defended, e. g. by Driesch, is
probably not incompatible with the hypothesis of prelocalized
areas of specific cytoplasmic stuffs in the body of the germ-
cells, as advocated by Conklin and Wilson. But anyhow the modern
theory of pre-delineation demands a regulating formative power in
the embryo just as necessarily as the epigenetic doctrine.
Moreover, in addition to the difficulty of epigenesis, the
inadequacy of mechanistic theories to account for the regeneration
of damaged parts of the embryo is becoming more clearly recognized
every day. The trend of the best scientific thought is clearly
evident in current biological literature. Thus Professor Wilson of
Columbia University in 1906 closes his admirable exposition of the
course of research over the whole field with the conclusion that
"the study of the cell has on the whole seemed to widen rather
than to narrow the enormous gap that separates even the lowest
form of life from the inorganic world " (The Cell, 434). In these
words, however, he is only affirming a fact to which the
distinguished Oxford biologist Dr. Haldane also testifies: "To any
physiologist who candidly reviews the progress of the last fifty
years, it must be perfectly evident that, so far from having
advanced towards a physico-chemical explanation of life, we are in
appearance very much farther from one than we were fifty years
ago. We are now more definitely aware of the obstacles to any
advance in this direction, and there is not the slightest
indication that they will be removed, but rather that with further
increase of knowledge and more refined methods of physical and
chemical investigation they will only appear more and more
difficult to surmount." (Nineteenth Century 1898, p. 403). Later
in Germany, Hans Driesch of Heidelberg became, perhaps, the most
candid and courageous advocate of vitalism among German biologists
of the first rank. From 1899 he proclaimed his belief in the
"autonomy" and "dynamical teleology" of the organism as a whole.
The vital factor he boldly designates" entelechy", or "psychoid",
and advocated a return to Aristotle for the most helpful
conception of the principle of life. His views on some points were
unfortunately and quite unnecessarily, as it seems to us,
encumbered by Kantian metaphysics -- and he appeared not to have
adequately grasped the Aristotelian notion of entelechy as a
constitutive principle of the living being. Still he has furnished
valuable contributions both to science and the philosophy of life.

Side by side with this vitalistic movement there continued an
energetic section of representatives of the old mechanical school
in men like Hackel, Loeb, Le Dantec, and Verworn, who have
attempted physico-chemical explanations; but no new arguments have
been adduced to justify their claims. Many others, more cautious,
adopt the attitude of agnosticism. This position, as Reinke justly
observes, has at least the merit of dispensing from the labour of
thinking. The present neo-vitalistic reaction, however, as the
outcome of very extensive and thorough-going research, is, we
venture to think, the harbinger of a widespread return to more
accurate science and a sounder philosophy in respect to this great
problem. With regard to the question of the origin of life, the
whole weight of scientific evidence and authority during the past
half century has gone to demonstrate with increasing cogency
Harvey's axiom Omne vivens ex vivo, that life never arises in this
world save from a previous living being. It claims even to have
established Virchow's generalization (1858) Omnis cellula ex
cellula, and even Flemming's further advance (1882), Omnis nucleus
e nucleo.

The history of vitalism, which we have thus briefly outlined,
shows how the advance of biological research and the trend of the
best modern scientific thought is moving steadily back in the
direction of that conception of life to be found in the scholastic
philosophy, itself based on the teaching of Aristotle. We shall
now attempt a fuller positive treatment of the doctrine adopted by
the great body of Catholic philosophers.

II. DOCTRINE

A. Science

Life is that perfection in a living being in virtue of which it is
capable of self-movement or immanent action. Motion, thus
understood includes, besides change of locality, all alterations
in quality or quantity, and all transition from potentiality to
actuality. The term is applied only analogically to God, who is
exempt from even accidental modification. Self-movement of a being
is that effected by a principle intrinsic to the nature of the
being, though it may be excited or stimulated from without.
Immanent action is action of which the terminus remains within the
agent itself, e. g. thought, sensation, nutrition. It is
contrasted with transient action, of which the effect passes to a
being distinct from the agent, e. g. pushing, pulling, warming,
etc. Immanent activity can be the property only of a principle
which is an intrinsic constituent of the agent. In contrast with
the power of self-movement inertia is a fundamental attribute of
inanimate matter. This can only be moved from without. There are
three grades of life essentially distinct: vegetative, sentient or
animal, and intellectual or spiritual life; for the capacity for
immanent action is of three kinds. Vegetative operations result in
the assimilation of material elements into the substance of the
living being. In animal conscious life the vital act is a
modification of the sentient organic faculty whilst in rational
life the intellect expresses the object by a purely spiritual
modification of itself. Life as we know it in this world is always
bound up with organized matter, that is, with a material structure
consisting of organs, or heterogeneous parts, specialized for
different functions and combined into a whole.

The ultimate units of which all organisms, whether plant or animal
are composed, are minute particles of protoplasm, called cells.
But even in the cell there is differentiation in structural parts
and in function. In other words, the cell itself living apart is
an organism. The complexity of living structures varies from that
of the single cell amoeba up to the elephant or man. All higher
organisms start from the fusion of two germcells, or gametes. When
these are unequal the smaller one -- the spermatozoon -- is so
minute in relation to the larger, or ovum, that their fusion is
commonly spoken of as the fertilization of the ovum by the
spermatozoon. The ovum thus fertilized is endowed with the power,
when placed in its appropriate nutrient medium, of building itself
up into the full-sized living being of the specific type to which
it belongs. Growth throughout is effected by a continuous process
of cell cleavage and multiplication. The fertilized ovum undergoes
certain internal changes and then divides into two cells
juxtaposed. Each of the pair passes through similar changes and
subdivides in the same way, forming a cluster of four like cells,
then of eight, then of sixteen and so on. The specific shape and
different organs of the future animal only gradually manifest
themselves. At first the cells present the appearance of a bunch
of grapes or the grains of a mulberry, the morula stage; the
growth proceeds rapidly, a cavity forms itself inside and the
blastosphere stage is reached. Next, in the case of invertebrates,
one part of the sphere invaginates or collapses inwards and the
embryo now takes the shape of a small sac, the gastrula stage. In
vertebrates instead of invagination there is unequal growth of
parts and the development continuing, the outlines of the nervous
system, digestive cavity, viscera, heart, sense-organs, etc.
appear, and the specific type becomes more and more distinct,
until there can be recognized the structure of the particular
animal -- the fish, bird, or mammal. The entire organism, skin,
bone, nerve, muscle, etc. is thus built up of cells, all derived
by similar processes ultimately from the original germ cell. All
the characteristic features of life and the formative power which
constructs the whole edifice is thus possessed by this germ-cell,
and the whole problem of life meets us here.

The chief phenomena of life can be seen in their simplest form in
a unicellular organism, such as the amoeba. This is visible under
the microscope as a minute speck of transparent jelly-like
protoplasm, with a nucleus, or a darker spot, in the interior.
This latter, as Wilson says, may be regarded as "a controlling
centre of cell activity ". It plays a most important part in
reproduction, and is probably a constituent part of all normal
cells, though this point is not yet strictly proved. The amoeba
exhibits irritability or movement in response to stimulation. It
spreads itself around small particles of food, dissolves them, and
absorbs the nutritive elements by a process of intussusception,
and distributes the new material throughout its substance as a
whole, to make good the loss which it is constantly undergoing by
decomposition. The operation of nutrition is an essentially
immanent activity, and it is part of the metabolism, or waste and
repair, which is characteristic Or living organisms. The material
thus assimilated into the living organism is raised to a condition
of chemically unstable equilibrium, and sustained in this state
while it remains part of the living being. When the assimilation
exceeds disintegration the animal grows. From time to time certain
changes take place in the nucleus and body of the cell, which
divides into two, part of the nucleus, reconstituted into a new
nucleus, remaining with one section of the cell, and part with the
other. The separated parts then complete their development, and
grow up into two distinct cells like the original parent cell.
Here we have the phenomenon of reproduction. Finally, the cell may
be destroyed by physical or chemical action, when all these vital
activities cease. To sum up the account of life in its simplest
form, in the words of Professor Windle:

The amoeba moves, it responds to stimuli, it breathes and it
feeds, it carries on complicated chemical processes in its
interior. It increases and multiplies and it may die. (What is
Life?, p. 36.)

B. Philosophy

These various phenomena constituting the cycle of life cannot,
according to the Schoolmen, be rationally conceived as the outcome
of any collection of material particles. They are inexplicable by
mere complexity of machinery, or as a resultant of the physical
and chemical properties of matter. They establish, it is
maintained, the existence of an intrinsic agency, energy, or
power, which unifies the multiplicity of material parts, guides
the several vital processes, dominates in some manner the physical
and chemical operations, controls the tendency of the constituents
of living substance to decompose and pass into conditions of more
stable equilibrium, and regulates and directs the whole series of
changes involved in the growth and the building-up of the living
being after the plan of its specific type. This agency is the
vital principle; and according to the Scholastic philosophers it
is best conceived as the substantial form of the body. In the
Peripatetic theory, the form or entelechy gives unity to the
living being, determines its essential nature, and is the ultimate
source of its specific activities. The evidence for this doctrine
can be stated only in the briefest outline.

(1) Argument from physiological unity

The physiological unity and regulative power of the organism as a
whole necessitate the admission of an internal, formal,
constituent principle as the source of vital activity. The living
being -- protozoon or vertebrate, notwithstanding its
differentiation of material parts and manifoldness of structure,
is truly one. It exercises immanent activity. Its organs for
digestion, secretion, respiration, sensation, etc., are organs of
one being. They function not for their own sakes but for the
service of the whole. The well-being or ill-being of each part is
bound up in intimate sympathy with every other. Amid wide
variations of surroundings the livine organism exhibits remarkable
skill in selecting suitable nutriment; it regulates its
temperature and the rate of combustion uniformly within very
narrow limits, it similarly controls respiration and circulation -
- the composition of the blood is also kept unchanged with
remarkable exactness throughout the species. In fact, life
selects, absorbs, distributes, stores various materials of its
environment for the good of the whole organism, and rejects waste
products, spending its energy with wonderful wisdom. This would
not be possible were the living being merely an aggregate of atoms
or particles of matter in local contact. Each wheel of a watch or
engine -- nay each part of a wheel -- is a being quite distinct
from, and in its existence intrinsically independent of every
other. No spoke or rivet sickens or thrives in sympathy with a bar
in another part of the machine, nor does it contribute out of its
actual or potential substance to make good the disintegration of
other parts. The combination is artificial; the union accidental,
not natural. All the actions between the parts are transient, not
immanent. The phenomena of life thus establish the reality of a
unifying and regulating principle, energy, or force, intimately
present to every portion of the living creature, making its
manifold parts one substantial nature and regulating its
activities.

(2) Morpho-genetic argument: Growth

The tiny fertilized ovum placed in a suitable medium grows rapidly
by division and multiplication, and builds up an infinitely
complex structure, after the type of the species to which it
belongs. But for this something more than the chemical and
physical properties of the material elements engaged is required.
There must be from the beginning some intrinsic formative power in
the germ to direct the course of the vast series of changes
involved. Machines may, when once set up be constructed to perform
very ingenious operations. But no machine constructs itself, still
less can it endow a part of its structure with the power of
building itself up into a similar machine. The establishment of
the doctrine of epigenesis has obviously increased indefinitely
the hopelessness of a mechanical explanation. When it is said that
life is due to the organization of matter, the question at once
arises: What is the cause of the organization? What but the
formative power -- the vital principle of the germ cell? Again the
growing organism has been compared to the building up of the
crystal. But the two are totally different. The crystal grows by
mere aggregation of external surface layers which do not affect
the interior. The organism grows by intussusception, the
absorption of nutriment and the distribution of it throughout its
own substance. A crystal liberates energy in its formation and
growth. A living body accumulates potential energy in its growth A
piece of crystal too is not a unity. A part of a crystal is still
a crystal. Not so, a part of a cow. A still more marvellous
characteristic of life is the faculty of restoring damaged parts.
If any part is wounded, the whole organism exhibits its sympathy;
the normal course of nutrition is altered the vital energy
economizes its supplies elsewhere and concentrates its resources
in healing the injured part. This indeed is only a particular
exercise of the faculty of adaptation and of circumventing
obstacles that interfere with normal activity, which marks the
flexibility of the universal working of life, as contrasted with
the rigidity of the machine and the immutability of physical and
chemical modes of action.

The argument in favour of a vital principle from growth was
reinforced by the introduction of experiment into embryology.
Roux, Driesch, Wilson, and others, showed that in the case of the
sea-urchin, amphioxus, and other animals, if the embryo in its
earliest stages, when consisting of two cells, four cells, and in
some cases of eight cells, be carefully divided up into the
separate single cells, each of these may develop into a complete
animal, though of proportionately smaller size. That is, the
fertilized ovum which was naturally destined to become one normal
animal, though prevented by artificial interference from achieving
that end, has yet attained its purpose by producing several
smaller animals; and in doing so has employed the cells which it
produced to form quite other parts of the organism than those for
which they were normally designed. This proves that there must be
in the original cell a flexible formative power capable of
directing the vital processes of the embryo along the most devious
paths and of adapting much of its constituent material to the most
diverse uses.

(3) Psychical Argument

Finally, we have immediate and intimate knowledge of our own
living conscious unity. I am assured that it is the same ultimate
principle within me which thinks and feels, which originates and
directs my movements. It is this same principle which has governed
the growth of all my sense-organs and members, and animates the
whole of my body. It is this which constitutes me one rational,
sentient, living being.

All these various classes of facts prove that life is not
explicable by the mechanical, physical, and chemical properties of
matter. To account for the phenomena there is required within the
living being a principle which has built up the organism after a
definite plan; which constitutes the manifold material a single
being; which is intimately present in every part of it; which is
the source of its essential activities; and which determines its
specific nature. Such is the vital principle. It is therefore in
the Scholastic terminology at once the final, the formal, and even
the efficient cause of the living being.

C. Unity of the Living Being

In each animal or plant there is only one vital principle one
substantial form. This is obvious from the manner in which the
various vital functions are controlled and directed to one end --
the good of the whole being. Were there more than one vital
principle, then we should have not one being but a collection of
beings. The practice of abstraction in scientific descriptions and
discussions of the structure and functions of the cell has
sometimes occasioned exaggerated notions as to the independence
and separateness of existence of the individual cell, in the
organism. It is true that certain definite activities and
functions are exercised by the individual cell as by the eye or
the liver; and we may for convenience consider these in isolation:
but in concrete reality the cell, as well as the eye or the liver
exerts its activity by and through the living energy of the whole
being. In some lowly organisms it is not easy to determine whether
we are in presence of an individual being or a colony; but this
does not affect the truth of the proposition that the vital
principle being the substantial form, there can only be one such
principle animating the living being. With respect to the nature
of this unity of form there has been much dispute among the
adherents of the Scholastic philosophy down to the present day. It
is agreed that in the case of man the unity, which is of the most
perfect kind, is founded on the simplicity of the rational or
spiritual soul. In the case of the higher animals also it has been
generally, though not universally held that the vital principle is
indivisible. With respect to plants and lower forms of animal life
in which the parts live after division, the disagreement is
considerable. According to some writers the vital principle here
is not simple but extended, and the unity is due merely to its
continuity. According to others it is actually simple, potentially
manifold, or divisible in virtue of the nature of the extended
organism which it animates. There does not seem to be much
prospect of a final settlement of the point.

D. Ultimate Origin of Life

The whole weight of the evidence from biological investigation, as
we have already observed, goes to prove with constantly increasing
force that life never appears on the earth except as originating
from a previous living being. On the other hand science also
proves that there was a time in the past when no life could have
possibly existed on this planet. How then did it begin? For the
Christian and the Theist the answer is easy and obvious. Life must
in the first instance have been due to the intervention of a
living First Cause. When Weismann says that for him the assumption
of spontaneous generation is a "logical necessity" (Evolution
Theory, II, 366), or Karl Pearson, that the demand for "special
creation or an ultrascientific cause" must be rejected because "it
would not bring unity into the phenomena of life nor enable us to
economize thought" (Grammar of Science, 353) we have merely a
psychological illustration of the force of prejudice even in the
scientific mind. A better sample of the genuine scientific spirit
and a view more consonant with actual evidence are presented to us
by the eminent biologist, Alfred Russel Wallace who, in concluding
his discussion of the Darwinian theory, points out that there are at least three stages in the development of the organic
world when some new cause or power must necessarily have come into
action. The first stage is the change from inorganic to organic,
when the earliest vegetable cell, or the living protoplasm out of
which it arose, first appeared. This is often imputed to a mere
increase of complexity of chemical compounds; but increase of
complexity with consequent instability, even if we admit that it
may have produced protoplasm as a chemical compound, could
certainly not have produced living protoplasm -- protoplasm which
has the power of growth and of reproduction, and of that
continuous process of development which has resulted in the
marvellous variety and complex organization of the whole vegetable
kingdom. There is in all this something quite beyond and apart
from chemical changes, however complex; and it has been well said
that the first vegetable cell was a new thing in the world,
possessing altogether new powers -- that of extracting and fixing
carbon from the carbon dioxide of the atmosphere that of
indefinite reproduction, and still more marvellous, the power of
variation and of reproducing those variations till endless
complications of structure and varieties of form have been the
result. Here, then, we have indications of a new power at work,
which we may term vitality, since it gives to certain forms of
matter all those characters and properties which constitute Life
("Darwinism", London, 1889, 474 5).

For a discussion of the relation of life to the law of the
conservation of energy, see ENERGY, where the question is treated
at length.

Having thus expounded what we believe to be the teaching of the
best science and philosophy respecting the nature and immediate
origin of life, it seems to us most important to bear constantly
in mind that the Catholic Church is committed to extremely little
in the way of positive definite teaching on the subject. Thus it
is well to recall at the present time that three of the most
eminent Italian Jesuits, in philosophy and science, during the
nineteenth century Fathers Tongiorgi, Secchi, and Palmieri,
recognized as most competent theologians and all professors in the
Gregorian University, all held the mechanical theory in regard to
vegetative life, whilst St. Thomas and the entire body of
theologians of the Middle Ages, like everybody else of their time,
believed implicitly in spontaneous generation as an everyday
occurrence. If therefore these decayed scientific hypotheses
should ever be rehabilitated or -- which does not seem likely --
be even established, there would be no insuperable difficulty from
a theological standpoint as to their acceptance.

MICHAEL MAHER
Transcribed by Tomas Hancil

From the Catholic Encyclopedia, copyright (c) 1913 by the
Encyclopedia Press, Inc. Electronic version copyright (c) 1996 by
New Advent, Inc.

Taken from the New Advent Web Page (www.knight.org/advent).

This article is part of the Catholic Encyclopedia Project, an
effort aimed at placing the  entire Catholic Encyclopedia 1913
edition on the World Wide Web. The coordinator is Kevin Knight,
editor of the New Advent Catholic Website. If you would like to
contribute to this  worthwhile project, you can contact him by e-
mail at (knight.org/advent). For  more information please download
the file cathen.txt/.zip.

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