The Divine Comedy was written by Dante Alighieri in the Renaissance, or "Age of Enlightenment" era. This epic poem describes Dante's journey into and through Hell, to Purgatory, and then finally to Heaven. At the very beginning of his journey, when he is about to go through Hell, Dante encounters three beasts - a wolf, lion, and leopard (Alighieri 1.33-60).. In heraldic terms, a lion and a wolf were good to have on your shield. But a leopard...?
In heraldry, a leopard is bad news. Thanks to the French who call the English lion passant léopard-lionné and the lion rampant guardant lion-léopardé. Because of this, the leopard has been mixed up and mistaken with the lion for a long, long time - it wasn't until spots were added to the leopard that the leopard was really noticed (Fox-Davies 173). On top of that, According to The Medieval Bestiary, the appearance of a leopard on a shield meant that the first bearer of the arms was born from adultery. On top of that, a leopard was thought to be the bastard offspring of a lion and a "pard" according to Medieval writers ("Medieval Bestiary").