Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

When Galilei let balls of a particular weight, which he had determined himself, roll down an inclined plain, or TorricelU made the air carry a weight, which he had previously determined to be equal to that of a definite volume of water; or when, in later times, Stahl^ changed metal into lime, and lime again into metals, by withdrawing and restoring something, a new [p. xiii] light flashed on all students of nature. They comprehended that reason has insight into that only, which she herself produces on her own plan, and that she must move forward with the principles of her judgments, according to fixed law, and compel nature to answer her questions, but not let herself be led by nature, as it were in leading strings, because otherwise accidental observations, made on no previously fixed plan, will never converge towards a necessary law, which is the only thing that reason seeks and requires. Reason, holding in one hand its principles, according to which concordant phenomena alone can be admitted as laws of nature, and in the other hand the experiment, which it has devised according to those principles, must approach nature, in order to be taught by it : but not in the character of a pupil, who agrees to everything the master likes, but as an appointed judge, who compels the witnesses to answer the questions which he himself proposes. Therefore even the science of physics entirely owes the beneficial revolution in its character to the happy thought, that we ought to seek in nature (and not [p. xiv]

^ I am not closely following here the course of the history of the experimental method, nor are the first beginnings of it very well known.

692 Supplement II 2import into it by means of fiction) whatever reason must learn from nature, and could not know by itself, and that we must do this in accordance with what reason itself has originally placed into nature. Thus only has the study of nature entered on the secure method of a science, after having for many centuries done nothing but grope in the dark.

Metaphysic, a completely isolated and speculative science of reason, which declines all teaching of experience, and rests on concepts only (not on their application to intuition, as mathematics), in which reason therefore is meant to be her own pupil, has hitherto not been so fortunate as to enter on the secure path of a science, although it is older than all other sciences, and would remain, even if all the rest were swallowed up in the abyss of an all-destroying barbarism. In metaphysic, reason, even if it tries only to understand a prioj'i (as it pretends to do) those laws which are confirmed by the commonest experience, is constantly brought to a standstill, and we are obliged again and again to retrace our steps, because they do not lead us where we want to go ; while as to any unanimity among those who are engaged [p. xv] in the same work, there is so little of it in metaphysic, that it has rather become an arena, specially destined, it would seem, for those who wish to exercise themselves in mock fights, and where no combatant has, as yet, succeeded in gaining an inch of ground that he could call permanently his own. It cannot be denied, therefore, that the method of metaphysic has hitherto consisted in groping only, and, what is the worst, in groping among mere concepts.