Figure Studies: Seated Female Holding a Book, Two Heads of Bearded Men, Seated Male Nude, and Four Sketches for Christ Judging (recto); Studies for Cain Slaying Abel (verso)

Public domain photo of Italian sculpture, 16th-17th century, free to use, no copyright restrictions image - Picryl description.

Cain and Abel - the first two sons of Adam and Eve. According to the book of Genesis, Cain, a farmer, became jealous of Abel, a shepherd, when God accepted Abel's offering of animal sacrifice but rejected Cain's offering of crops. In a fit of anger, Cain killed Abel, making him the first murderer in human history. God punished Cain by marking him and banishing him from the land.