A man must not always tell all, for that were folly: but what a man says should be what he thinks, otherwise ‘tis knavery. I do not know what advantage men pretend to by eternally counterfeiting and dissembling, if not never to be believed when they speak the truth; it may once or twice pass with men
 Michel de Montaigne, The Essays of Michel de Montaigne (1580). copy citation

add
Author Michel de Montaigne
Source The Essays of Michel de Montaigne
Topic truth pretending
Date 1580
Language English
Reference
Note Translated by Charles Cotton
Weblink http://www.gutenberg.org/files/3600/3600-h/3600-h.htm

Context

“My soul naturally abominates lying, and hates the very thought of it. I have an inward shame and a sharp remorse, if sometimes a lie escapes me: as sometimes it does, being surprised by occasions that allow me no premeditation. A man must not always tell all, for that were folly: but what a man says should be what he thinks, otherwise ‘tis knavery. I do not know what advantage men pretend to by eternally counterfeiting and dissembling, if not never to be believed when they speak the truth; it may once or twice pass with men; but to profess the concealing their thought, and to brag, as some of our princes have done, that they would burn their shirts if they knew their true intentions, which was a saying of the ancient Metellius of Macedon;” source