Phaedo

Socrates teaches that the essences of things—greatness or smallness, beauty or ugliness, newness or oldness—exist apart from the world but imbue the objects of life, so that, say, a flower takes on the attributes of beauty, color, aroma, and so forth. Within objects, forms become visible: “these you can touch and see and perceive with the senses, but the unchanging things you can only perceive with the mind” (37).

These attributes, though they enter into objects, never achieve perfect representation in them. All things in the world, then, are imperfect; their beauty and color and hardness never quite approach purity in the ideals on which they’re based.

The forms are so fundamental that people are born knowing them. Though we never see true perfection in any quality, we can easily imagine it.

Attributes always appear as pairs of opposites: Light appears as a contrast to dark, cold stands apart from heat, and youth compares with old. Otherwise, for example, “if there were no alternation of sleeping and waking, […] all other things would be asleep, too,” and sleepers would “not be distinguishable from the rest” (32). Likewise, if everything were dead, there would no longer be a distinction between life and death.