If there be no science of the common man, still less is there a science of the different man, since the manifestation of this difference makes him solitary and unique, that is to say, incomparable. Yet, just as there is a general physiology, so there is a general psychology, also. Whatever their nature, all the beasts of the earth breathe the same air, and the brain of the genius, like that of the ordinary mortal, derives its primordial form from sensation. We have only a rough idea by what mechanism sensation is transformed into action. All we know is that the intervention of consciousness is not needed to bring about this transformation. We know also that this intervention may prove harmful through its power to modify the predetermined logic, to break the series of associations in order to create in the mind the first link of a new volitional chain. Consciousness, which is the principle of liberty, is not the principle of art. It is possible to express quite clearly what has been conceived in the unconscious shades. Intellectual activity, far from being intimately allied with the functioning of consciousness, is more often disconcerted by it. We listen badly to a symphony, when we know we are listening. We think badly, when we know we are thinking. Consciousness of thinking is not thought. The subconscious state is the state of automatic cerebration in full freedom, while intellectual activity pursues its course at the extreme limit of consciousness, a little below it and beyond its reach. Subconscious thought may remain for ever unknown. It may, on the other hand, come to light, either at the precise moment when the automatic activity ceases, or later--even after several years. These facts of cogitation do not, then, belong to the domain of the unconscious, properly speaking, since they can become conscious. Besides, it will doubtless be preferable to reserve to this rather vast word the meaning given it by a particular philosophy. The subconscious state differs also from the state of dreams, though dreams may be one of its manifestations. The dream is almost always absurd, with a special sort of absurdity, and is incoherent or orderly, according to its associations which are entirely passive,[2] and whose procession differs even from that of ordinary passive associations, conscious or unconscious.[3]