It is by the goodness of God that in our country we have those three unspeakably precious things: freedom of speech, freedom of conscience, and the prudence never to exercise either of them.
Mark Twain (1835-1910) American writer [pseud. of Samuel Clemens]
Following the Equator, ch. 20, Epigraph (1897)
(Source)
Cited as from Pudd'nhead Wilson's New Calendar. Sometimes misquoted "... never to practice either."