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