• The means by which Descartes recognizes the indubitability of his existence, is often referre to as his cogito. This is Latin for ‘I think’, and comes from the phrase cogito ergo sum (‘I think therefore I am’), a phrase which does not appear in the Meditations but does appear (in French) in the Discourse and (in Latin) in the later Principles of Philosophy. The full phrase suggests an argument, but it is a peculiar sort of argument and you should try (as commentators on Descartes continue to do) to formulate for yourself what is going on here.

• Descartes knows more than the mere fact that he exists, the second part of the meditation starts to outline this wider range of knowledge. Notice that he does this by asking what sort of thing he is—i.e., by asking what his substance is.

• If the second part of the meditation opened his patch of bedrock beyond his mere existence, the third can be seen to set limits on what he can be certain of. At the same time, it points to the character of a second sort of substance. So pay attention not only to how he grasps the wax but also to what he grasps about it. Pay attention also to an opposition he is setting up between imagining and perceiving on the one hand and some other sorts of thinking, especially conceiving, on the other.