If we now pass to the examination of the most delicate organs of our body,--the brain and the nervous system,--we see that the motions executed within these organs are likewise limited in their evolutions. I employ these simple terms expressly, that I may be better understood. We perceive these motions in the form of sensations or thoughts. Are we free to be hot or cold, to be hungry or thirsty? Are we independent of the ideas that come to us, the images that are formed in our mind, that is to say, our brain? No, most assuredly. At least, then, we are free to receive them or reject them, to show them the door or smilingly invite them in? Here we reach the crux of the question, for it is at this point that the will intervenes. What, indeed, is the will? The will is nothing more than the realization, effected by our mind, that of two motives one is more powerful than the other. The will is perhaps the least voluntary and the least free element in our make-up. Before it declares itself, we are often in a state that gives us the illusion of liberty. We are still in ignorance as to whether we shall go to right or to left. These moments of vacillation are sometimes agreeable and sometimes disagreeable. Most often they pass unperceived, and we find ourselves started on one of the two paths, totally unawares. Our will has acted mechanically. Our mind has worked like an automatic scale. Whatever we do, there is a cause, and this cause itself depends upon another, and so on to infinity. If I am at this moment smoking a cigar, it is because Christopher Columbus discovered America. The search for causes leads to authentications of this order. But our acts have only a single direct cause. Several influences have combined and weighed upon the lever. Often, when we reflect upon the motives for our acts, we imagine that we have found them, yet the most important motive has escaped us. To enter into examples of this would be to enter the absurd; Pascal has given one which has become famous,--his epigram about Cleopatra's nose. It is saying little to aver that effects and causes are united like the links of a chain. I see effects and causes rather in the guise of an extremely complicated fabric, of which every thread depends upon the others. But such a representation may not be made materially. Let it suffice for us to understand and to admit that none of our actions is the beginning of a series. There is only a single series, which does not seem to have had a beginning and whose end it is impossible to foresee.