“To believe all men honest would be folly. To believe none so, is something worse.”
John Quincy Adams (1767–1848) American politician, 6th president of the United States (in office from 1825 to 1829)
Letter to William Eustis http://books.google.com/books?id=S088AAAAIAAJ&pg=PA319 (22 June 1809), published in Writings of John Quincy, Adams (1914), The Macmillan company. <br class="br">Variant: All men profess honesty as long as they can. To believe all men honest would be folly. To believe none so is something worse.