What is an idea?
It is an image painted upon my brain.
Are all your thoughts, then, images?
Certainly; for the most abstract thoughts are only the consequences of all the objects that I have perceived. I utter the word "being" in general, only because I have known particular beings; I utter the word "infinity," only because I have seen certain limits, and because I push back those limits in my mind to a greater and still greater distance, as far as I am able. I have ideas in my head only because I have images.
And who is the painter of this picture?
It is not myself; I cannot draw with sufficient skill; the being that made me, makes my ideas.
And how do you know that the ideas are not made by yourself?
Because they frequently come to me involuntarily when I am awake, and always without my consent when I dream.
You are persuaded, then, that your ideas belong to you only in the same manner as your hairs, which grow and become white, and fall off, without your having anything at all to do with the matter?
Nothing can possibly be clearer; all that I can do is to frizzle, cut, and powder them; but I have nothing to do with producing them.