Thomas Paine: "The mind once enlightened ..."

cannot again become dark.

"The mind once enlightened cannot again become dark. There is no possibility, neither is there any term to express the supposition by, of the mind unknowing any thing it already knows; and therefore all attempts ... will be like persuading a seeing man to become blind, and a sensible one to turn an idiot. The first of which is unnatural and the other impossible.”
Thomas Paine
[slightly abridged from LETTER TO THE ABBE REYNAL

True? Not true?

Image Sol by Antonio Nunziati