Their remains but the third class, the superstitious. These worthies were not content merely to rest in ignorance; they must know all about things which had no existence whatever.
Restait en dernier lieu la classe superstitieuse des ignorants; ceux-lá ne se contentent pas d'ignorer, ils savent ce qui n'est pas.
Original text (French)
Notes from Wikiquote
Ch. VI: The Permissive Limits of Ignorance and Belief in the United States (Charles Scribner's Sons "Uniform Edition", 1890, p. 31) | Tr. Walter James Miller (1978)
Variants
There was the class of superstitious people; they are not content simply to ignore what is true, they also believe what is not true.