Suppose then that I am dreaming - it isn’t true that I, with my eyes open, am moving my head and stretching out my hands. Suppose, indeed that I don’t even have hands or any body at all. Still, it has to be admitted that the visions that come in sleep are like paintings: they must have been made as copies of real things; so at least these general kinds of things - eyes, head, hands and the body as a whole - must be real and not imaginary. For even when painters try to depict sirens and satyrs with the most extraordinary bodies, they simply jumble up the limbs of different kinds of real animals, rather than inventing natures that are entirely new. If they do succeed in thinking up something completely fictitious and unreal - not remotely like anything ever seen before - at least the colours used in the picture must be real. Similarly, although these general kinds of things - eyes, head, hands and so on - could be imaginary, there is no denying that certain even simpler and more universal kinds of things are real. These are the elements out of which we make all our mental images of things - the true and also the false ones.

Well, then, what am I? A thing that thinks. What is that? A thing that doubts, understands, affirms, denies, wants, refuses, and also imagines and senses. That is a long list of attributes for me to have - and it really is I who have them all. Why should it not be? Isn’t it one and the same ‘I’ who now doubts almost everything, understands some things, affirms this one thing - ·namely, that I exist and think·, denies everything else, wants to know more, refuses to be deceived, imagines many things involuntarily, and is aware of others that seem to come from the senses? Isn’t all this just as true as the fact that I exist, even if I am in a perpetual dream, and even if my creator is doing his best to deceive me? Which of all these activities is distinct from my thinking? Which of them can be said to be separate from myself?

The fact that it is I who doubt and understand and want is so obvious that I can’t see how to make it any clearer. But the ‘I’ who imagines is also this same ‘I’. For even if (as I am pretending) none of the things that I imagine really exist, I really do imagine them, and this is part of my thinking. Lastly, it is also this same ‘I’ who senses, or is aware of bodily things seemingly through the senses. Because I may be dreaming, I can’t say for sure that I now see the flames, hear the wood crackling, and feel the heat of the fire; but I certainly seem to see, to hear, and to be warmed. This cannot be false; what is called ‘sensing’ is strictly just this seeming, and when ‘sensing’ is understood in this restricted sense of the word it too is simply thinking. All this is starting to give me a better understanding of what I am.

But I still can’t help thinking that bodies - of which I form mental images and which the senses investigate - are much more clearly known to me than is this puzzling ‘I’ that can’t be pictured in the imagination. It would be surprising if this were right, though; for it would be surprising if I had a clearer grasp of things that I realize are doubtful, unknown and foreign to me - ·namely, bodies· - than I have of what is true and known - namely my own self. But I see what the trouble is: I keep drifting towards that error because my mind likes to wander freely, refusing to respect the boundaries that truth lays down. Very well, then; I shall let it run free for a while, so that when the time comes to rein it in it won’t be so resistant to being pulled back.