Of all the systems of morality, ancient or modern, which have come under my observation, none appear to me so pure as that of Jesus. He who follows this steadily need not, I think, be uneasy, although he cannot comprehend the subtleties and mysteries erected on his doctrines by those who, calling themselves his special followers and favorites, would make him come into the world to lay snares for all understandings but theirs. These metaphysical heads, usurping the judgment seat of God, denounce as his enemies all who cannot perceive the Geometrical logic of Euclid in the demonstrations of St. Athanasius, that three are one, and one is three; and yet that the one is not three nor the three one.
Letter to William Canby (18 September 1813).