What's wrong with Maybe?

The World I Live In

I have refused to live
locked in the orderly house of
reasons and proofs.
The world I live in and believe in
is wider than that. And anyway,
what's wrong with Maybe?

You wouldn't believe what once or
twice I have seen. I'll just
tell you this:
only if there are angels in your head will you
ever, possibly, see one.

Mary Oliver, 'Felicity'