When I see words like "demarcation" / "definition" / "outline" /
  "circumscribe" - they're all very visual terms for me. I
  mentally *see* a pencil line drawn around a 'something'. So for
  me, it's only an abstraction in that it's not drawn on paper
  (which is also an abstraction but you 'get' what I mean) but
  it's written very much the same internally. So, In my "mind's
  eye" [use your favorite metaphor for imagination whatever
  works]: For sympathy, I see an oval and a square. The oval is
  sympathizing with the square. You can tell this is sympathy
  because you can see a mini form of the square inside of the
  oval. For empathy, I see an oval and a square. The oval is
  empathizing with the square. You can tell this is empathy
  because a ghostly form of the square is superimposed upon the
  oval, without the oval losing its original shape. However, it is
  possible for the oval to forget it is an oval and believe it has
  become the square. Such is the danger of empathy and what
  happens when we watch movies and feel what the character feels.