 And yet, according to you, says Sanches to his reader, this Being that is admittedly beyond your understanding “is the cause of everything; and therefore, according to your definition, understanding of Him is necessary for the understanding of His works”, which only proves that “you know nothing” (TNK: 196). It was this, Sanches’ fideism that probably saved him from a fate similar to that of Giordano Bruno’s. Sanches’ target was Aristotelian epistemology, never faith. He denied not only knowledge of efficient and first causes, but also of material and formal causes. Aristotle’s answers to sundry philosophical matters failed to convince him. When Aristotle wrote in the Posterior Analytics that “[s]ome hold that, owing to the necessity of knowing the primary premises, there is no scientific knowledge” (1.3 72b5–6), he was addressing the very sceptical notion of knowledge held by someone like Sanches. “Our own doctrine”, wrote Aristotle, “is that not all knowledge is demonstrative: on the contrary, knowledge of the immediate premises is independent of demonstration” (1.3 72b18–20, my emphasis). But this is exactly the problem for Sanches; for if primary and immediate premises do not require demonstration, that means one has perfect knowledge of them, as one would of first causes (like God), but that is not true. And if one does not have perfect knowledge of primary and immediate premises, then where do they come from? What makes an indemonstrable primary premise the guarantor of knowledge? Nothing, answers Sanches. Primary premises are inventions that we need to take on faith in order to elude an infinite regress, and end up in the kind of scepticism that Aristotle wanted to avoid. However, if, as Aristotle proposed, “demonstration must be based on premises prior to and better known than the conclusion” (1.3 72b25–26), and demonstrations were based on premises that were themselves arbitrary inventions, then demonstrations were not to be taken as reflecting perfect knowledge, or as Sanches would have it, any knowledge at all. Sanches writes: