Etymologically, 'sympathy' comes from the Greek and means 'feeling with'. Although there is a distinction between feeling well-disposed or helpful and feeling similar or like someone, the connection is that in general if one feels similar to someone one is more disposed to feel well about them and be helpful to them, and conversely if one feels well about someone or is helpful to them, the ordinary human-all-too-human reason is that one believes they are of one's own kind.

In any case, the capacity for sympathy is basic for much behavior that is ethical or moral in the positive sense, and also the basis of many if not all agreements between people.