love to indulge the most wayward and fantastic beliefs. In these we see the enemies of science, unwilling learners in Nature's school, rebellious spirits who fain would fashion the universe to their own liking. The first condition, therefore, of scientific thinking is to recognize and to bow to Nature as the supreme teacher, and to feel that she has an inexhaustible fund of wisdom to impart. He who thinks scientifically recognizes no authority save that of demonstration. lie gladly avails himself of the help of superior minds, but he does not swear by their words; for, great as they may be, and as he may acknowledge them to be, he can not regard them as infallible. Partisanship in science is almost a contradiction in terms. The expression "schools of thought" even is one to be accepted with caution; seeing that no one should wittingly attach himself to any school save the great school that Nature keeps ever open to all. Too much emphasis, indeed, can hardly be laid upon this view of the matter. The pursuit of truth partakes of the character of a religion; and the mind that is imbued with the religion of science never for a moment places any human authority, however great, in the place of the truth which, by no violent figure of speech, he may be said to adore. Truth has its ministers, but it has no priests, no class of men whose mere office summons to reverence. We ask respecting the ministers of truth simply how much of its illumination they have received, how much they are able to impart; and we honor them in proportion to the clearness and strength of their thought and the fruitfulness of their labors.
The more we dwell upon and develop the thought of Nature as the teacher, the more we see that the whole of scientific thinking depends upon loyalty to this one source of light. Every unscientific attitude of mind or movement of thought we ever heard of has had, for its main characteristic, an ignoring of Nature and a following after idols whose power was supposed to be superior to Nature. In all ages men have more or less resented the blessed bonds that have made them captive to earth and to its laws. Because their thought could traverse the heavens, and because their imagination could conjoin the most opposite elements and conditions, they have sighed after equal liberty for their active powers, and have run eagerly after whatever promised to emancipate them from the ordinary conditions of life. Hence the fanaticisms that have possessed and oppressed mankind; hence most of the delusions to which they have fallen subject; hence the scorn that, under certain systems of thought, has been, and is still, cast upon this present life; hence the prevailing indifference to, and depreciation of, what claims no higher sanction than natural or human law.
In the study of Nature there is one caution to be observed, and that is that absolute truth is not to be expected. Nature is willing to teach us, but she treats us like the children we are, using the symbols best suited to the range of our comprehension, but not laying bare her ultimate secrets. A large part of the scientific temper consists in recognizing this. He who imagines that, because he has made a generalization under which a certain group of facts can be advantageously presented and explained, he has struck the rock-bed of eternal truth, is a scholar rather pert than solid, and Nature will probably rebuke him some day. Newton knew well that in his great generalization he had merely succeeded in measuring a force the real nature of which it was wholly beyond him to explain; and the greatest scientific intellects of the present day are precisely those that most fully acknowledge, because they most deeply feel, the merely provisional character of the most important scientific hypotheses.