What is there in Yeats' poetry which makes him a modern poet?

I think that one of Keats' strongest elements of modernism
would be in how he was so open to embracing a sense of negative capability.  Keats was
ahead of his time in suggesting that it is impossible for individuals to know
everything, and that living with the unknown is an acceptable part of consciousness.  Of
course, this becomes a source of liberation for Keats, making him distinctly different
from his modern counterparts.  In poems like "Ode on a Grecian Urn," the striving for
totality and a sense of transcendent truth is something that exists outside the realm of
the human being and that is "all ye need to know."  In other poems such as "La Belle
Dame Sans Merci," there is a truly puzzling element to figure out moral values such as
who is right and who is wrong.  In the end, Keats' poetry forces the reader to accept
the idea that negative capability is something that is evident in consciousness and in
being.  One might wish to repel it, but Keats suggests that this is impossible.  In
this, Keats is echoing the modern thinkers who will also argue that there are levels of
understanding that exist outside the grasp of human
understanding.