So Simple and So Beautiful.

Behind it all is surely an idea so simple, so beautiful, that when we grasp it - in a decade, a century, or a millennium - we will all say to each other, how could it have been otherwise? How could we have been so stupid?
~ John Archibald Wheeler, Source: 'How come the Quantum (α)', Annals of the New York Academy of Sciences, 480 (1986), pp. 304-316.