Angels can fly because they can take themselves lightly... Seriousness is not a virtue. It would be a heresy, but a much more sensible heresy, to say that seriousness is a vice. It is really a natural trend or lapse into taking one's self gravely, because it is the easiest thing to do... It is much easier to write a good Times leading article than a good joke in Punch. For solemnity flows out of men naturally; but laughter is a leap. It is easy to be heavy: hard to be light. Satan fell by the force of gravity.-- G.K. Chesterton in Orthodoxy
UPDATE: the original embedded video clip (at YouTube) was removed due to copyright restrictions. Comedy Central has it available on their website: Colbert interviews Philip Zimbardo, author of The Lucifer Effect
"Hat tip" to Marcel LeJeune, The Catholic Evangelist, who sent along the link.