"All series A B C … are accompanied by α β γ." [The A B C … series of Dr. Carus has a different meaning from mine.]
"We may represent motion or we may represent mind as the basis of the world, or we may conceive them as being on equal terms." [I cannot agree with a co-ordination of "motion" and "mind.">[
"They [viz. feeling and motion] are as inseparable as are the two sides of a sheet of paper." [Fechner says, "As inseparable as the concave and convex sides of the same circle." This appears to me an inapposite simile in so far as a duality is predicated where in my view a unity alone exists.]
My view of the problem is as follows: We have colors, sounds, pressures, and so forth (A B C …), which, as simplest component parts, make up the world. In addition thereto, percepts (resolvable into α β γ …), feelings, and so forth, more or less composite. How α β γ … differ from A B C … I will not define here, for I do not know exactly. It is enough for the time being that they do differ from A B C …, as the latter do from one another. And let us now leave α β γ … entirely out of account and put ourselves in a time and state in which there are only A B C. Now I say, that if I see a tree with green leaves (A), with a hard (B), gray (C) trunk, that A B C are elements of the world. I say elements—and not sensations, also not motions—because it is not my purpose at this place to arrive at either a psychological or a physiological or a physical theory, but to proceed descriptively. The every-day man, indeed, takes greenness, grayness, hardness, or complexes thereof it may be, for constituent parts of the world—for he does not trouble himself about a psychologico-physiological theory—and does not learn moreover anything more about the world; from his point of view he is right. Similarly, for the descriptive physicist the question is also one merely of the dependencies of A B C … on one another; for him too A B C …, or complexes thereof, are and remain constituent parts of the world.
If, however, I close my eye (K), withdraw my feeling hand (L), A B C … disappear. If I contemplate A B C … in this dependence they are my sensations. This is but a special point of view within the first.
According to my conception, therefore, the same A B C … is both element of the world (the "outer" world, namely) and element of feeling.
The question how feeling arises out of the physical element has for me no significance, since both are one and the same. The parallelism stands to reason, since each is parallel to itself. It is not two sides of the same paper (which latter is invested with a metaphysical rôle in the simile), but simply the same thing.
A perfect physics could strive to accomplish nothing more than to make us familiar beforehand with whatever it were possible for us to come across sensorily; that is, we should have knowledge of the interrelation of A B C. A perfect psychology would supply the interrelation of α β γ. Leaving out of account the theoretical intermediaries of physics—physiology and psychology—questions like "How does feeling arise from motion" would never come up. However, the artificial inventions of a physical or psychological theory, must not be introduced into a general discussion of this character—for they are necessarily "one-sided."
I may now set forth my differing point of view with regard to the idea of "motion." A motion is either perceptible by the senses, as the displacing of a chair in a room or the vibration of a string, or it is only supplied, added (hypothetical), like the oscillation of the ether, the motion of molecules and atoms, and so forth. In the first instance the motion is composed of A B C …, it is itself merely a certain relation between A B C …, and plays therefore in the discussion now in hand no especial part. In the second instance the hypothetical motion, under especially favorable circumstances, can become perceptible by the senses. In which case the first instance recurs. As long as this is not the case, or in circumstances in which this can never happen (the case of the motions of atoms and molecules), we have to do with a noumenon, that is, a mere mental auxiliary, an artificial expedient, the purpose of which is solely to indicate, to represent, after the fashion of a model, the connection between A B C …, to make it more familiar to us. It is a thing of thought, an entity of the mind (α β γ …). I cannot believe that this is to be co-ordinated with A B C … in the same way as A B C … among each other are. Putting together motion and feeling goes as much against me as would say the co-ordination of numbers and colors. Perhaps I stand quite alone in this, for physicists have accustomed us to regard the motions of atoms as "more real" than the green of trees. In the latter I see a (sensory) fact, in the former a Gedankending, a thing of thought. The billions of ether-vibrations which the physicist for his special purposes mentally annexes to the green, are not to be co-ordinated with the green, which is given immediately.
When a piece of zinc and a piece of copper, united by a wire, are dipped in sulphuric acid and deflect a magnetic needle in the vicinity of the wire, the unprepossessed discoverer of the fact discerns naught of motion beyond the deflection of the needle and the diffusion in the fluid. Everything reverts to certain combinations of A B C. Electricity is a thing of thought, a mental adjunct; its motion another; its magnetic field still another. All these noumena are implements of physical science, contrived for very special purposes. They are discarded, cast aside, when the interconnection of A B C … has become familiar; for this last is the very gist of the affair. The implement is not of the same dignity, or reality, as A B C …, and must not be placed in the same category, must not be co-ordinated with it where general considerations are involved to which physics with its special objects does not extend.