| 416 | Beautiful harmony comes from things that are in opposition to one another [Heraclitus] |
| 425 | A thing can have opposing tensions but be in harmony, like a lyre [Heraclitus] |
| 232 | Opposites are as unlike as possible [Plato] |
| 627 | If everything is made of opposites, are the opposed things made of opposites? [Aristotle] |
| 628 | Not everything is composed of opposites; what, for example, is the opposite of matter? [Aristotle] |