Men's minds are as variant as their faces, and, where the motives of their actions are pure, the operation of the former is no more to be imputed to them as a crime, than the appearance of the latter; for both, being the work of nature, are alike unavoidable.
Source, in full
Letter to Benjamin Harrison V (9 March 1789), published in Washington's Writings: Being His Correspondence, Addresses, Messages, and Other Papers, Official and Private, Selected and Published from the Original Manuscripts, Volume IX, p. 475.