“I find both humor and grimness in most issues.”

Essay as "Mr. X" (1969)
Context: Incidentally, I find that reasonably good insights can be remembered the next day, but only if some effort has been made to set them down another way. If I write the insight down or tell it to someone, then I can remember it with no assistance the following morning; but if I merely say to myself that I must make an effort to remember, I never do.
I find that most of the insights I achieve when high are into social issues, an area of creative scholarship very different from the one I am generally known for.

Letter http://books.google.com/books?id=R8ksAAAAIAAJ&q=%22I+own+any+form+of+humor+shows+fear+and+inferiority+Irony+is+simply+a+kind+of+guardedness+So+is+a+twinkle+It+keeps+the+reader+from+criticism%22+%22Humor+is+the+most+engaging+cowardice%22&pg=PA166#v=onepage to Louis Untermeyer (10 March 1924)
General sources
Context: I own any form of humor shows fear and inferiority. Irony is simply a kind of guardedness. So is a twinkle. It keeps the reader from criticism. Whittier, when he shows any style at all is probably a greater person than Longfellow as he is lifted priestlike above consideration of the scornful. Belief is better than anything else, and it is best when rapt, above paying its respects to anybody's doubt whatsoever. At bottom the world isn't a joke. We only joke about it to avoid an issue with someone to let someone know that we know he's there with his questions: to disarm him by seeming to have heard and done justice to this side of the standing argument. Humor is the most engaging cowardice.

BALIW
Source: The Manila Tribune. April 19, 1928.

Leslie Berger (January 28, 1982) "A Little Night Humor", The Washington Post, C1.

Unjust Judgments (1874)
Miscellany
Context: Humor is, however, nearer right than any emotion we have. Humor is the atmosphere in which grace most flourishes.

Song Anatole of Paris