There's a class of brain cells called mirror neurons, which act as a neural Wi-Fi, attuning to the other person's internal state moment to moment and recreating that state in our own brain—their emotions, their movements, their intentions. This means empathy is not just based on reading the external signs of someone else's feelings, like the hint of a frown, or the irritation in their voice, but because of mirror neurons, we ‘tune in’ to their state of mind.
Once we shift our attention to a particular person, we automatically sense their state of mind, and if they're in immediate distress, we are wired to help them. The design of the social brain creates a three-step process: First we notice, then we feel with, and then we respond to.
Neural interconnection may partly explain the tradition in Asian cultures of darshan - simply being in the presence of a realized being. People go to be with someone who has stabilized an equanimous, loving awareness. And because the social brain makes their state of mind contagious to anyone in their presence, those beings transmit a taste of their mind-state to those around them. So the point of darshan is just going to be in that presence, because you come away with a bit of what they have. 
- *Daniel Goleman, Tricycle interview, Winter 2006.