Copernicus admitted, “It is not necessary that hypotheses should be true, or even probable; it is sufficient that they lead to results of calculation which agree with calculations. * * Neither let any one, so far as hypotheses are concerned, expect anything _certain_ from astronomy; since that science can afford nothing of the kind; lest, in case he should adopt for truth things feigned for another purpose, he should leave this study more foolish than he came. * * The hypothesis of the terrestrial motion was _nothing but an hypothesis_, valuable only so far as it explained phenomena, and not considered with reference to absolute truth or falsehood.” The Newtonian and all other “systems of nature” are little better than the “hypothesis of the terrestrial motion” of Copernicus. The foundations or premises are always unproved; no proof is ever attempted; the necessity for it is denied; it is considered sufficient that the assumptions shall _seem_ to explain the phenomena selected. In this way it is that one theory supplants another; that system gives way to system as one failure after another compels opinions to change. This will ever be so; there will always exist in the mind a degree of uncertainty; a disposition to look upon philosophy as a vain pretension; a something almost antagonistic to the highest aspirations in which humanity can indulge, unless the practice of theorising be given up, and the method of simple inquiry, the “zetetic” process be adopted. “Nature speaks to us in a peculiar language; in the language of phenomena, she answers at all times the questions which are put to her; and such questions are experiments.”[2] Not experiments only which corroborate what has previously been _assumed_ to be true; but experiments in every form bearing on the subject of inquiry, before a conclusion is drawn or premises affirmed. [2] “Liebig’s Agricultural Chemistry,” p. 39. We have an excellent example of zetetic reasoning in an arithmetical operation; more especially so in what is called the “Golden Rule,” or the “Rule-of-Three.” If one hundred weight of any article is worth a given sum, what will some other weight of that article be worth? The separate figures may be considered as the elements or facts of the inquiry; the placing and working of these as the logical arrangement; and the quotient or answer as the fair and natural deduction. Hence, in every zetetic process, the conclusion arrived at is essentially a quotient, which, if the details be correct, must, of necessity, be true beyond the reach or power of contradiction.