واعلم أنه قد ينتزع الشبه أي التماثل من نفس التضاد
Know that apparent resemblance may sometimes be derived from opposition itself.
Ordinary simile presents a feature shared by the terms. Rhetorical speech, however, can exploit opposed qualities for a special effect. This does not mean bravery and cowardice have literally become the same property.
Calling a coward “a lion,” in a context that makes the cowardice unmistakable, sets the expected quality of bravery against its absence in the actual subject. The effect lies in the collision between description and reality, allowing mockery, wit or ironic judgment to emerge.