Thomas Hobbes (1750). “The Moral and Political Works of Thomas Hobbes of Malmesbury: Never Before Collected Together : To which is Prefixed, the Author's Life, Extracted from that Said to be Written by Himself, ...”, p.119
RENE DESCARTES (1952). “RULES FOR THE DIRECTION OF THE MIND DISCOURSE ON THE METHOD MEDITATIONS ON FIRST PHILOSOPHY OBJECTIONS AGAINST THE MEDITATIONS AND REPLIES THE GEOMETRY”