Maybe a more interesting figurative use of the heart is that of the constant worker. Why would the heart actually have a larger magnetic field than the brain? Because it's a powerful muscle whose action is precisely timed. The heart's unconscious working is, of course, necessary for every other part of the body and mind, but the body and mind must in turn provide the heart with prudent maintenance, so there's a bit about interdependence.
And where does that leave questions of intuition, emotion, and reason? With a different metaphor. Maybe the gut. I hear a lot of blood goes there.