Fleas can be taught nearly anything that a Congressman can.

Fleas can be taught nearly anything that a Congressman knows. Illustration from AMERICAN EXAMINER, 1910 from the Dave Thomson collection
– What Is Man?
…the smallest minds and the selfishest souls and the cowardliest hearts that God makes.
– Letter fragment, 1891
Suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself.
– Mark Twain, a Biography
Congressman is the trivialist distinction for a full grown man.
– Notebook #14, Nov. 1877 – July 1878
All Congresses and Parliaments have a kindly feeling for idiots, and a compassion for them, on account of personal experience and heredity.
– Mark Twain’s Autobiography; also in Mark Twain in Eruption
The lightning there is peculiar; it is so convincing, that when it strikes a thing it doesn’t leave enough of that thing behind for you to tell whether–Well, you’d think it was something valuable, and a Congressman had been there.
– Mark Twain’s Speeches, “The Weather”
It could probably be shown by facts and figures that there is no distinctly native American criminal class except Congress.
– Pudd’nhead Wilson’s New Calendar
It is the foreign element that commits our crimes. There is no native criminal class except Congress.
– More Maxims of Mark, Johnson, 1927
Whiskey is carried into committee rooms in demijohns and carried out in demagogues.
– Notebook, 1868
…I never can think of Judas Iscariot without losing my temper. To my mind Judas Iscariot was nothing but a low, mean, premature, Congressman.
– “Foster’s Case,” New York Tribune, 10 March 1873
A man with a new idea is a crank — until the idea succeeds.