 At times, Descartes seems to allow that there are some truths – such as the simple propositions of mathematics – that can never be doubted, but in darker moods that carry the day he worries whether an omnipotent deceiver might beguile us even about these. Malebranche, however, is more impressed by Descartes’ first inclination. That I exist, that I have various thoughts, and that twice two equals four are not subject to deception but are known by what Malebranche calls ‘simple perception,’ by which the mind ‘perceives a simple thing without any relation to anything else whatsoever’ (Search 1.2, OC 1:49; LO 7). He opposes simple perception to reasoning or inference: whereas the former consists in a direct or immediate grasp of something, reasoning constitutes an indirect apprehension and involves more than one mental act (Schmaltz 1996, 24). Because of the latter, reasoning requires the use of memory, which is subject to error and deception: