is false, we shall never say that he is certain. For by certainty we mean something positive (II. xliii. and note), not merely the absence of doubt.
However, in order that the foregoing proposition may be fully explained, I will draw attention to a few additional points, and I will furthermore answer the objections which may be advanced against our doctrine. Lastly, in order to remove every scruple, I have thought it worth while to point out some of the advantages, which follow therefrom. I say "some," for they will be better appreciated from what we shall set forth in the fifth part.
I begin, then, with the first point, and warn my readers to make an accurate distinction between an idea, or conception of the mind, and the images of things which we imagine. It is further necessary that they should distinguish between idea and words, whereby we signify things. These three—namely, images, words, and ideas—are by many persons either entirely confused together, or not distinguished with sufficient accuracy or care, and hence people are generally in ignorance, how absolutely necessary is a knowledge of this doctrine of the will, both for philosophic purposes and for the wise ordering of life. Those who think that ideas consist in images which are formed in us by contact with external bodies, persuade themselves that the ideas of those things, whereof we can form no mental picture, are not ideas, but only figments, which we invent by the free decree of our will; they thus regard ideas as though they were inanimate pictures on a panel, and, filled with this misconception, do not see that an idea, inasmuch as it is an idea, involves an affirmation or negation. Again, those who confuse words with ideas, or with the affirmation which an idea involves, think that they can wish something contrary to what they feel, affirm, or deny. This misconception will easily be laid aside by one, who reflects on the nature of knowledge, and seeing that it in