based on the strong ground of soundest modern knowledge, or how far only on such knowledge as was available in the earlier and ruder stages of culture where their types were shaped. It has to be maintained that the early history of man has its bearing, almost ignored as that bearing has been by those whom it ought most stringently to affect, on some of the deepest and most vital points of our intellectual, industrial, and social state.
Even in advanced sciences, such as relate to measure and force and structure in the inorganic and organic world, it is at once a common and a serious error to adopt the principle of letting bygones be bygones. Were scientific systems the oracular revelations they sometimes all but pretend to be, it might be justifiable to take no note of the condition of mere opinion or fancy that preceded them. But the investigator who turns from his modern text-books to the antiquated dissertations of the great thinkers of the past, gains from the history of his own craft a truer view of the relation of theory to fact, learns from the course of growth in each current hypothesis to appreciate its raison d'être and full significance, and even finds that a return to older starting-points may enable him to find new paths, where the modern track seems stopped by impassable barriers. It is true that rudimentary conditions of arts and sciences are often rather curious than practically instructive, especially because the modern practitioner has kept up, as mere elementary processes, the results of the ancient or savage man's most strenuous efforts. Perhaps our tool-makers may not gain more than a few suggestive hints from a museum of savage implements, our physicians may only be interested in savage recipes so far as they involve the use of local drugs, our mathematicians may leave to the infant-school the highest flights of savage arithmetic, our astronomers may only find in the star-craft of the lower races an uninstructive combination of myth and common-place. But there are departments of knowledge, of not less consequence than mechanics and medicine, arithmetic and
