Let us imagine, just for a moment, one of our nerves--the optic nerve, for instance--transformed into a hollow tube, along which the emissions of miniatures should wend their way. In this case, evidently, if so strange a disposition were to be realised, and if B could see what was flowing in the optic nerve of A, he would experience a sensation almost analogous to that of A. Whenever the latter saw a dog, a sheep, or a shepherd, B would likewise see in the optic canal minute dogs, microscopic sheep, and Lilliputian shepherds. At the cost of such a childish conception, a parity of content in the sensations of our two spectators A and B might be supposed. But I will not dwell on this. The above considerations seem to me to explain the difference generally noticed between thought and the physiological process. It is not a difference of nature, an opposition of two essences, or of two worlds--it is simply a difference of object; just that which separates my visual perception of a tree and my visual perception of a dog. There remains to know in what manner we understand the relation of these two processes: this is another problem which we will examine later. Since the content does not give us the differentiation we desire, we will abandon the definitions of psychology by content. What now remains? The definitions from the point of view. The same fact may he looked at, like a landscape, from different points of view, and appears different with the changes therein. It is so with the facts we consider psychical, and the autonomy of psychology would thus be a matter of point of view. It has, then, been supposed--and this is a very important proposition--that the distinctive feature of psychical facts does not consist in their forming a class of particular events. On the contrary, their characteristic is to be studied in their dependency on the persons who bring them about. This interesting affirmation is not new: it may be read in the works of Mach, Kuelpe, Muensterberg, and, especially, of Ebbinghaus, from whom I quote the following lines of quite remarkable clearness: "Psychology is not distinguished from sciences like physics and biology, which are generally and rightly opposed to it, by a different content, in the way that, for instance, zoology is distinguished from mineralogy or astronomy. It has the same content, but considers it from a different point of view and with a different object. It is the science, not of a given part of the world, but of the whole world, considered, however, in a certain relation. It studies, in the world, those formations, processes, and relations, the properties of which are essentially determined by the properties and functions of an organism, of an organised individual.... Psychology, in short, considers the world from an individual and subjective point of view, while the science of physics studies it as if it were independent of us."