A poem should be palpable and mute
As a globed fruit, (1-2)
In other words, we should sense a poem but not feel as if it's hitting us over the head with a sledgehammer on purpose. So art and poetry should work in a way that's sensual, but not overexerting itself in purpose and effort.
A poem should be wordless
As the flight of birds. (7-8)
Yea, yea, you've heard it a million times already, but it's got a certain "wordless" and effortless ring to it, which is how good poetry should read. It should "say" things without necessarily shouting things in our ears. It should sound free like the flitting birds high above us.
A poem should be motionless in time
As the moon climbs, (9-10)
Good poetry should also be timeless. It should endure all the moving and shaking of the times and be just as natural and fluid as the moon climbing in the sky. So essentially, it should tap into those parts of our humanity that are just as timeless.
A poem should be equal to:
Not true. (17-18)
Everyone got that? Take out your graphing paper and slide rules, and make a note. Poetry does not equal truth, in the capital T, only-one-reality sense of the word "truth." Poetry is not supposed to describe reality, it's supposed to evoke it and inspire our own individualized reflections (truths, plural, and with a lower-case "t").
A poem should not mean
But be. (23-24)
Words to live by, all you budding young poets. Don't torture your reader with your "insights"; inspire them with your sense of the world around you.