First one gets works of art, then criticism of them, then criticism of the criticism, and, finally, a book on The Literary Situation, a book which te… - Randall Jarrell

A poem is sort of an onion of contexts, and you can no more locate any of the important meanings exclusively in a part than you can locate a relation in one of its terms. The significance of a part may be greatly modified or even in extreme cases completely reversed by later and larger parts and by the whole.

...most of the people in a war never fight for even a minute — though they bear for years and die forever. They do not fight, but only starve, only suffer, only die: the sum of all this passive misery is that great activity, War.

A successful poem says what a poet wants to say, and more, with particular finality. The remarks he makes about his poems are incidental when the poem is good, or embarrassing or absurd when it is bad — and he is not permitted to say how the good poem is good, and may never know how the bad poem is bad. It is better to write about other people's poetry.