Every animal is sad after coitus except the human female and the rooster.
Triste est omne animale post coitum, praeter mulierem gallumque
Employment is Nature's physician, and is essential to human happiness.
But it is best of all to look at the human skeleton with your own eyes.
Quote text and notes from Wikiquote: Galen (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.