As Eileen Simpson recounts in her marvelous book Poets in Their Youth, Berryman and Lowell used to play a game where they challenged each other to name the three best lines in English. Berryman's, as I recall, were from Yeats' "The Wild Swans at Coole."
For a long time mine were from Keats' "Ode to a Nightingale":
"But here there is no light
Save what from heaven is with the breezes blown
Through verdurous gloom and winding mossy ways."
Later, it was Pound, in the late Cantos:
"Do not move.
Let the wind speak
that is paradise."
I won't say that the two lines below, from Edwin Rolfe's "First Love," have replaced either Keats or Pound for me. But they're certainly worth quoting.
"and always I think of my friend who amid the apparition of bombs
saw on the lyric lake the single perfect swan."