In the Second Meditation, after achieving his first piece of certainty, that of his own existence as a thinker, Descartes’ meditator allows his mind to relax and return to its old habit of trusting the senses to give him information about what exists in the world around him and about the nature of such things. What he first attends to is a piece of wax, fresh from the honeycomb and still retaining the scent of the flowers the bees had visited. It is white and solid, but when put by the fire it becomes liquid and transparent and can be formed into countless shapes. The senses of sight and touch inform us only of its temporary states, and even imagination cannot cover all its possible shapes. It is intellect or reason that tells us what is always true of it – namely, that is an extended, flexible, and changeable thing – just as it was reason that assured him that he was a thinking thing with countless changing thoughts.

Although the wax is contrasted with himself, since its existence is not certain yet, it also gives him a model for himself, and the passage prepares us for the claim in the Sixth Meditation that there are just two sorts of finite substance, thinking substance and extended substance. The wax is his first sample of extended substance, where extension is true of it throughout its changes, just as thought is true of himself throughout all his ever-changing conscious states. The implicit comparison between his mind, with its countless thoughts, and the wax, and its countless shapes, makes the wax a sort of image of himself. “Is it not the same ‘I’ who is now doubting almost everything, who nonetheless understands some things, who affirms that this one thing is true, desires to know more, is unwilling to be deceived, imagines many things even involuntarily, and is aware of many things which apparently come form the senses?” (AT VII 28, CSM II 19). Later he adds: