What do you think he means by "you see things and you say "why?", but I dream things that never were and I say "why not?"
It's very modern, very much in the mind of the new world.
At one point in the late 1400's, the people of Spain looked out on the vast ocean and said "who would travel such an expanse and chance meeting Leviathan or Death?" but we know whta one person said "I see a passage to India and spices."
Jules Verne made men walk on the moon and meet strange creatures in his mind and in his books. However, John Kennedy actually proposed making men walk on the moon and leave footprints.
To see the world not as it is but as it is possible is a great gift.