Where did the idea that the heart representing compassion and love come from?

Your heart responds physically to strong emotions, thus the presumption that is where they come from.

Great love hits you in the chest. I don’t know why. It just does.

In an interesting, and yet not totally unrelated twist; Ancient Jewish people considered the kidneys the seat of all emotions.

I think the idea of the human heart being the seat of all emotions comes from Ancient Greece.

Ever had a broken heart? That should tell it all.

The heart is an involuntary muscle. Some would say that love is involuntary emotion.

The heart is the organ that feels while the brain rationalizes.

This article explaining symbols contains some interesting heart facts.

Ancient wisdom is relevant to today’s science: Broken Heart Syndrome

@SpatzieLover Indeed very interesting.

Vedic tradition (5000+ years old) holds the heart chakra, energy center, as the seat of emotions and empathy.