Well, there's at least somewhat of a biological basis for
  expressing one's feelings alongside one's thinking:* The
  amygdala ->prefrontal cortex circuit from the thalamus. It seems
  that the data stream (if one wants to use a computer-science
  analogy; it could easily be colored water in hoses) - goes from
  the thalamus and breaks up into two parallel streams, one for
  the prefrontal cortex and one for the amygdala. But the stream
  to the prefrontal cortex is slow and thin but the hose going to
  the amygdala is fat and fast; like a firehose. But then the
  amygdala feeds forward into the prefrontal cortex as well, with
  the force of a fireman's hose, influencing rational thought
  before rational thought even begins. that being said - the
  prefrontal cortex ALSO has a stream that feeds BACK into the
  amygdala, allowing one to utilize rational thought to inhibit or
  mitigate the power of the amygdala. But it's thin and slow and
  not a strong connection at first.* It can be built up through
  training (apparently), explaining the strength of many
  philosohpies/schools of thought/religions that have us "master
  our emotions". Yet, how much training does it take for your
  emotional to take over our rational thinking processes?* None,
  it seems! Emotion always influences reason [unless one has a
  damaged amygdala... ppl like that are in a perpetual state of
  reasoning... never able to commit to a decision because there's
  no emotional "push" to decide "true"/"false"/"best"/"worst"...
  must truly be a hell-on-earth.. .at least for those around them
  with functioning amygdalas]. So, in that sense, not that it's a
  requirement to pair up emotion and rational thought, it does
  make some biological sense.* At least, if one believes the whole
  circuitry notion of brain function anyhow.* We're still seeing
  what we want to see, after all, so that our scientific
  hypothesis and discoveries end up happening to match up to
  common patterns of existing human thought, it shouldn't be
  surprising. We've been primed to already :P