My distaste for the man was such that I hurried away, and went to sleep with a strange sadness, in the mood in which, as I suppose, believers pray; but that I was none. Dr. Materialismus had had a plum-colored velvet smoking-jacket on, with a red fez (he was a sort of beau), and I dreamed of it all night, and of the rushing leather band, and of the grinding of the ice in the river. Something made me keep my visit secret from Althea; an evil something, as I think it now. The following day we had a lecture on light. It was one in a course in physics, or natural philosophy, as it was called in B---- College; just as they called Scotch psychology “Mental Philosophy,” with capital letters; it was an archaic little place, and it was the first course that the German doctor had prevailed upon the college government to assign to him. The students sat at desks, ranged around the lecture platform, the floor of the hall being a concentric inclined plane; and Althea Hardy’s desk was next to mine. Materialismus began with a brief sketch of the theory of sound; how it consisted in vibrations of the air, the coarsest medium of space, but could not dwell in ether; and how slow beats--blows of a hammer, for instance--had no more complex intellectual effect, but were mere consecutive noises; how the human organism ceased to detect these consecutive noises at about eight per second, until they reappeared at sixteen per second, the lowest tone which can be heard; and how, at something like thirty-two thousand per second these vibrations ceased to be heard, and were supposed unintelligible to humanity, being neither sound nor light--despite their rapid movement, dark and silent. But was all this energy wasted to mankind? Adverting one moment to the molecular, or rather mathematical, theory--first propounded by Democritus, re-established by Leibnitz, and never since denied--that the universe, both of mind and matter, body and soul, was made merely by innumerable, infinitesimal points of motion, endlessly gyrating among themselves--mere points, devoid of materiality, devoid also of soul, but each a centre of a certain force, which scientists entitle _gravitation_, philosophers deem _will_, and poets name _love_--he went on to Light. Light is a subtler emotion (he remarked here that he used the word _emotion_ advisedly, as all emotions alike were, in substance, the subjective result of merely material motion). Light is a subtler emotion, dwelling in ether, but still nothing but a regular continuity of motion or molecular impact; to speak more plainly, successive beats or vibrations reappear intelligible to humanity as light, at something like 483,000,000,000 beats per second in the red ray. More exactly still, they appear first as _heat_; then as red, orange, yellow, all the colors of the spectrum, until they disappear again, through the violet ray, at something like 727,000,000,000 beats per second in the so-called chemical rays. “After that,” he