I'm going to declare this book as the ideal early-years first introduction to empathy. Bobo is a baby chimp living in the jungle and he has lost his mum. Everywhere he goes, he sees other baby animals being cuddled by one of their parents and he cries the same refrain on every page, "hug!". His desolation becomes almost unbearable when suddenly his mum bursts into the book for a heart-swelling reunion - which then turns into a hug-fest across the jungle. The book uses just two words: hug and Bobo, but tells a rich and emotional story that any small child can relate to - but doing so through the eyes of a baby chimp. Of all the little board books I read to my children when they were very young (I mean less than one), this was the one that most explicitly started to nuture their empathy. Here's a short video of it being read aloud.