'So they maintained it as certain that the judgments of the gods far surpass man’s grasp. This alone, of course, would have caused the truth to be hidden from the human race to eternity, if mathematics, which is concerned not with ends, but only with the essences and properties of figures, had not shown men another standard of truth. […]
That is why we have such sayings as: ‘So many heads, so many attitudes’, ‘everyone finds his own judgment more than enough,’ and ‘there are as many differences of brains as of palates.’ These proverbs show sufficiently that men judge things according to the disposition of their brain, and imagine, rather than understand them. For if men had understood them, the things would at least convince them all, even if they did not attract them all, as the example of mathematics shows.'
Spinoza, appendix to Book 1 of the Ethics, (a passage cited approvingly by both Badiou and Althusser)