ive imagination. He so presented his problems as to exercise their powers of investigation. He did not, like most teachers, make his pupils mere passive recipients, but made them active explorers.
As these facts imply. Prof. Tyndall's thoughts were not limited to physics and allied sciences, but passed into psychology; and though this was not one of his topics, it was a subject of interest to him. Led as he was to make excursions into the science of mind, he was led also into that indeterminate region through which this science passes into the science of being; if we can call that a science of which the issue is nescience. He was much more conscious than physicists usually are that every physical inquiry, pursued to the end, brings us down to metaphysics, and leaves us face to face with an insoluble problem. Sundry propositions which physicists include as lying within their domain do not belong to physics at all, but are concerned with our cognitions of matter and force: a fact clearly shown by the controversy at present going on about the fundamentals of dynamics. But in him the consciousness that there here exists a door which, though open, science can not pass through, if not always present, was ever ready to emerge. Not improbably his early familiarity with theological questions given him by the controversy between Catholicism and Protestantism, which occupied his mind much during youth, may have had to do with this. But whatever its cause, the fact, as proved by various spoken and written words, was a belief that the known is surrounded by an unknown, which he recognized as something more than a negation. Men of science may be divided into two classes, of which the one, well exemplified in Faraday, keeping their science and their religion absolutely separate, are untroubled by any incongruities between them; and the other of which, occupying themselves exclusively with the facts of science, never ask what implications they have. Be it trilobite or be it double-star, their thought about it is much like the thought of Peter Bell about the primrose. Tyndall did not belong to either class; and of the last I have heard him speak with implied scorn.
Being thus not simply a specialist but in considerable measure a generalist, willingly giving some attention to the organic sciences, if not largely acquainted with them, and awake to "the humanities," if not in the collegiate sense, yet in a wider sense—Tyndall was an interesting companion; beneficially interesting to those with brains in a normal state, but to me injuriously interesting, as being too exciting. Twice I had experience of this. When, after an injury received while bathing in a Swiss mountain-stream, he was laid up for some time, and, on getting back to England, remained at Folkestone, I went down to spend a few days