Cain and Abel
Cain kills Abel (in the background).
Baptistery at Florence, Italy
According to the Book of Genesis in the Bible, after Adam and Eve had to leave the Garden of Eden, they began to have children. The first one they named Cain, and the second they named Abel. When these two children grew up, Cain became a farmer and Abel became a shepherd (he took care of sheep).
Cain was very angry, and he killed his brother Abel. So God was angry with Cain, and made him go away and live in a country far away. And Adam and Eve had a third son, Seth.
This story shows a memory of the beginnings of farming and sheep-raising, which would have been around 10,000 BC. It also shows one of the oldest themes of Western Asia, which still continues today: the conflict between the settled farmer and the wandering shepherd, where each considers the other to be bad, and believes that God is on his side.
To buy an excellent Child's Bible, click on the picture (this is the one I learned from, and the one I give my own kids):