From Page 63:
[Chesterton said] "Angels can fly because they can take themselves lightly."
To be able to take oneself lightly, to be able to laugh at oneself, is one of the healthiest of human traits. It is one of the signs of our transcendence, one of the "rumors of angels" in us, a kind of divine antidote to the exaltation of the ego.
Chesterton's following insight about the opposite of taking oneself lightly is less well known:
"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. (Orthodoxy, P 128)"The devil fell because he took himself too seriously, that is, he did not acknowledge his dependence on God; he did not accept the obvious truth that he was not the center of the universe. Thus, taking himself so seriously, he doesn't have a sense of humor; and he certainly doesn't like to be laughed at. And those Christians—like Chesterton—who draw comic images, of him, well, he probably doesn't like that either."