It would seem, then, that the most positive of all sciences would be the science of mind; and the next most positive the sciences which enable us to draw conclusions from our positively existing mental states; the statements, we may call them, which our minds make to us. Yet, strange to say, the very first thing Positivism does is to dispense with a science of mind, as mind, altogether. Mr. Mill makes it a severe reproach against Comte, that he ignores both psychology and logic; recognizes no power in the mind, even of self-observation; accepts no theory even of the inductive process. Mr. Mill characterises Comte's want of mental science as "a grave aberration."[12] It is indeed so. This appears plainly enough in the example just adduced from our commonest sensation, the every-day phenomenon of colour. It was made up, you saw, of three factors, a physical antecedent, a condition of the sensitive apparatus, and a mind which received into its consciousness the impression instrumentally conveyed to it. This last, you will remember, was the first fact to us. It is the fact: the revelation of an outward world, its changes and its continuing presence, its rest and its constant motion. Without this fact of inward consciousness, nature would have possessed no more significance than pictures seen in the eyes of the newly dead.
Such being the case, it needs no argument to show the importance of making quite sure that our interpretation of nature is correct. If there be any unobserved illusion in our sensory instruments, or what must evidently be much worse, in our percipient mind, truth is at an end, and falsehood received in its stead. Hence the necessity of observing our own observations, subjecting our consciousness to scrutiny, and being acquainted with the criteria, not only of our perceptions, but of our judgments. It is this process of analysis and criticism which forms a large part of the method of verification,—a method the value of which did not escape the great Greek philosophers, though some recent writers seem to fancy it a modern discovery.
Inexperienced observers are often so little aware of the pre-eminent importance of this critical process, that I will detain you with an illustration of it for the benefit of my younger auditors. My example shall be taken from perception par excellence—our eyesight, the sense pronounced surest both in poetry and prose. You will remember your Horace
Segnius irritant animos demissa per aurem,
Quam quæ sunt oculis subjecta fidelibus, et quæ
Ipse sibi tradit spectator.
And almost everybody else has said the same, as witness the old proverb, "Seeing is believing." Now I will mention five instances in which people believe they see something, and do not see it; in other words, the objective antecedent is wanting, and the impression is produced partly by the sensory apparatus, partly by the mind itself. As I describe these instances one by one, let my hearers ask themselves, How does this illusion come about? Is it produced by our optic instrument or by our mental activity?
First, then, Take a lighted stick, and whirl it rapidly round and round. You believe you see a circle of sparks—in reality it is no more than a simple train, and on a like illusion the Catherine-wheel is constructed. Again, put yourself in the hands of an optically inclined friend, and let him operate upon you thus. He shall place a cardboard down the middle axis of your face, quite close against your nose—one side of his board, say the right, coloured a brilliant red, the left a vivid green. After an instant or two let him suddenly substitute another board, white on both sides. Do my young friends guess what will follow? Your right eye will see green, your left red—the reverse of what they saw before; yet neither will see correctly, for both eyes are looking at uncoloured surfaces.
Thirdly, Watch the full moon rising—how large and round she looks, resting as it were upon that eastern hill, and seen amidst the tops of its forest trees! How much larger and broader than when she hangs aloft in upper sky! Has every one here learned the true reason why? If not, look at her through a slit in a card, and her diameter will be the same. Fourthly, A schoolboy is crossing his bedroom in the deep dark night, anxiously hoping that his head may not come into collision with the bed-post. Though carefully and successfully avoiding it, he imagines of a sudden that the blow is imminent. Quick as thought he stops to save his head, and, behold, the room is as quickly filled with sparks or flames of fire. Another moment, and all becomes dark once more. I have heard many a schoolboy exclaim over this phenomenon, but never knew one who could explain it. Finally, did you ever, on opening your eyes in a morning, close them quickly again, and keep them shut, directing them as if to look straight forwards? Most persons of active nervous power, after a few trials—say a dozen, or a score—are surprised to see colours appear and flit before the sight. Some years ago, Germany's greatest poet tried, at the suggestion of her greatest physiologist, a series of experiments on these coloured images. He found that by an effort of will he could cause them to come and go, govern their movement, march, and succession. And this took place under no conditions of impaired sensation, nor any hallucination of a diseased mind. A thoroughly healthy will succeeded in impressing itself upon physical instruments, controlling their law, and creating at its own pleasure an unfailingly bright phantasmagoria.
Some here may, others may not, have apprehended the distinctions between our five cases. The first two are due to the sensory apparatus, its optical laws of continued impression and complementary colour. In the latter three, mind intervenes. The enlarged size of the moon occurs through rapid comparison, the fiery lights in a dark room through instinctive apprehension, both influences of mind on the sensory system. The fifth and most interesting of all is no bad example of interference between moral and material law. The will truly causative (you may remark) overrules the natural process of physical impression, alters it, and creates a designed effect. I wish I could induce my young friends to devise a number of experiments on similar mixed cases, and, having tried them, to dissect out their real laws. These sharpenings of the critical faculty are exceedingly useful—they cultivate clearness; and most people know that two-thirds among our mistakes in life are caused by confusion of thought.
Besides all other uses, such lessons teach at once the necessity, as we said before, of observing your own observations. And as, first, the real witness of every observation is our mind; every fact[168] which comes through our bodily senses being to us a mental impression, it seems but common sense to hear above all things what mind has to say for and about itself. Then, secondly, where would be the benefit derived from our observations, if we could not reason upon them, or could place no confidence in our own reasonings? Yet the art of reasoning is so purely a mental process, that it can be represented by symbols as abstract and free from material meaning as if they were bare algebraic signs. Thirdly, in the most accurate of sciences mind extends our knowledge far beyond the circle of observation, and gives us axiomatic assurance of its own accuracy. Who ever saw, or ever can see, all straight lines in all conceivable positions, yet who doubts that throughout the whole universe no two straight lines ever did inclose or can inclose a space? And, fourthly, can it be a matter of indifference to any of us what evidence the mind offers concerning its own moral nature, and what is the value of that evidence, and the laws deducible therefrom? How true it thus appears that "know thyself" lies at the root of all knowledge, and that the man who receives no witness from within can know nothing as he ought to know it!
Comte swept away all these and the like considerations by a neat little fiction of his own. We cannot observe ourselves observing, he said, we cannot observe ourselves reasoning. So, then, logic becomes a chimera, and psychology a word of contempt. Respecting this fallacy, Mr. Mill thinks the only wonder is that it should impose on any one. Clearly it imposed on Comte himself. But, "what organon," asks Mill, "for the study of our moral and intellectual functions does M. Comte offer in lieu of the direct mental observation which he repudiates? We are almost ashamed to say it is phrenology!" Mill regards this statement as a reductio ad absurdum, but the actual organon substituted is more absurd still. Comte's phrenology was not the phrenology of Gall or Spurzheim, but a funny small bantling of his own, a sort of "infant phenomenon," called into existence not without a Positive purpose. In plain words, mind was no longer to give evidence respecting itself. We must study its laws in brain. How any true correspondence of brain and mind could be known unless both were studied, does not appear. Comte overlooked the question in his anxiety to substitute for psychology and its laws a bodily function and its laws. Yet his motive appears to have been excellent! He regarded this dwarfed superficial phrenology, Mr. Mill tells us, "as extricating the mental study of man from the metaphysical stage, and elevating it to the positive." The chief gist of which sentence, bewildering to the uninitiated, opens up the very core and centre of the Positive system—a subject for dissection of some considerable human interest.