"Nature and Poetry Work on Maybe" Bill Viola on his favorite time of day

I have been thinking about this "in between" time a lot these days. Maybe it is because of the birds migrating "in between" seasons, maybe it is because I am drawn to the possibility of "what if" rather than "what is." I keep thinking of a phrase " when is becomes if" which I think may be from an ee cummings poem but I have not been able to locate it. If anyone finds it, please let me know.

Viola, in another video created at the Otis College Convocation, states that in the history of mysticism, all art rises out of the cloud of unknown. He later states that (forgot the source but it could be Buddhism) the gap between your desire and your ability is the most precious thing we have...and that is the inability to reach greatness.