In default of any other proof, the thumb would convince me of the existence of a God.

Attributed to Newton as "A défaut d'autres preuves, le pouce me convaincrait de l'existence de Dieu" in a treatise on palmistry: A later translation by Edward Heron-Allen renders the phrase as "In default of any other proofs, the thumb would convince me of the existence of God", and acknowledges that it does not seem to appear in any of Newton's works []

Reported as something said by Newton in a section on palmistry in Charles Dickens's All the Year Round (1864), Vol. 10, p. 346; later found in "The Book of the Hand" (1867) by A R. Craig, S. Low and Marston, p. 51 | "In want of other proofs, the thumb would convince me of the existence of a God; as without the thumb the hand would be a defective and incomplete instrument, so without the moral will, logic, decision, faculties of which the thumb in different degrees offers the different signs, the most fertile and the most brilliant mind would only be a gift without worth. [No closing quotations marks exist to specify the end of the quotation and the beginning of the author's commentary.] | A slight variant of this is cited as something Newton once "exclaimed" in Human Nature : An Interdisciplinary Biosocial Perspective, Vol. 1, Issues 7-12 (1978), p. 47: "In the absence of any other proof, the thumb alone would convince me of God's existence."