mjhjmtu

One trouble with pretending to be someone or something
else is that there is no stopping it. For Plato, the act of pretending
rapidly runs down through a sexist chain of being from
men to women to animals to inanimate objects, in a crescendo
of degradation. Socrates’s affirmation of this terrible danger
in poetry is the classic condemnation of imitation in the
Western tradition. Imitation is a species of dehumanizing
or unmanning (!) madness. Poetry, for Plato, has authority
all right, but it is the authority of radical evil. Therefore the
poets must be banished from his ideal republic.

I don't know in this context classic mean: traditional or typical or admired?

This passage is from a book named: On literature.

When something is "the classic something" it is the quintessential example of something or "the canonical example" of it.

Let's say that a person has a reputation for liking things to be very tidy. Let's call her Colleen since that's a convenient female name already present on this page and this example needs a woman's name. "Colleen" is invited to the home of her boyfriend, to meet his parents. No sooner is she in the door when she starts to rearrange the figurines on the mantelpiece.

The boyfriend might shrug helplessly and say:

That's classic Colleen.

He might speak about Colleen's penchant for tidiness from time to time over the course of their relationship, and may refer back to that occasion as the "classic case of tidying up":

That time at my parents house when Colleen started to rearrange the figurines on the mantelpiece is the classic case.

No other example of her desire to make things tidy surpasses that one. It is her boyfriend's "go to" story when he wants to speak of this aspect of her personality.