I'd say that Pound and Yeats are writing from direct personal if
extra-normal experience -- not from some paradigm shift introduced by the
theory of relativity.
Indeed there are *ancient* analogues for their experiences in myth. Pound
called  it 'busting out of the quotidian'.  See his poem "The Tree" for the
ur-statement.
Yeats's "Leda and The Swan" is similar.  I do believe Yeats goes a step
farther out than Pound in his involvement with spirits and mysteries and
otherworldly communication. For Pound it was _paradiso terrestre_.

in coitu illuminatio...
Tim Romano