A Mencken Chrestomathy
(New York: Vintage Books, 1982), p. 466:
An author, like any other so-called artist, is a man in whom the normal vanity of all men is so vastly exaggerated that he finds it a sheer impossibility to hold it in. His overpowering impulse is to gyrate before his fellow men, flapping his wings and emitting defiant yells. This being forbidden by the police of all civilized countries, he takes it out by putting his yells on paper. Such is the thing called self-expression.
Substitute "a blogger" for "an author" and "in his blog" for "on paper".