ISAAC, or, in Hebrew, Yitsḥaq; the second of the biblical patriarchs and the only son of Abraham and Sarah. Although not known from elsewhere, the name Yitsḥaq conforms to a well-known Northwest Semitic type and means "may God smile"; Ugaritic texts from the thirteenth century BCE refer to the benevolent smile of the Canaanite god El. The Bible, however, ascribes the laughter to Isaac's mother, who was amazed to learn that she would have a child despite her advanced age.

Isaac is the only patriarch whose name was not changed. The Bible treats him primarily as Abraham's son or the father of Jacob and Esau. He was the first ancestor of the Israelites to be circumcised on his eighth day in accordance with God's command (Gn. 17:12). At an unspecified age he was taken to be sacrificed in order to test Abraham's faithfulness; however, Isaac himself did...