It's the story of Kronos, youngest of the Titans. He first castrated his father Gaia, the sky, and then killed him, by his mothers orders, and took the throne. His mother warned him that he would receive the same fate. So he swallowed each of his children. However, Zeus was hidden by his mother. When he grew up, he cut open Kronos' stomach, freeing his brothers and sisters, and threw him with the rest of the titans into exile.