- One cannot change one's own nature.
- 1597, , Act i, Scene 1 (First Folio): King. Lyons make Leopards tame.Mowbray. Yea but not change his spots.
- 1611, , 13:23: Can the Ethiopian change his skin, or the leopard his spots?
- 1820, , Chapter 32: End now all unkindness. Let us put the Jew to ransom, since the leopard will not change his spots, and a Jew he will continue to be.
- 1918, , : The leopard cannot change his spots, old boy.