We come a little closer to the problem when we recognize that every scientific inquiry passes historically through at least four stages. (_a_) The first of these stages is, if I may be allowed the bull, that in which scientific inquiry does not take place at all, because no problem or difficulty in the quality of the experience has presented itself to provoke reflection. We have only to cast our eye back from the existing status of any science, or back from the status of any particular topic in any science, to discover a time when no reflective or critical thinking busied itself with the matter--when the facts and relations were taken for granted and thus were lost and absorbed in the value which accrued from the experience. (_b_) After the dawning of the problem, there comes a period of occupation with relatively crude and unorganized facts--the hunting for, locating, and collecting of raw material. This is the empiric stage, which no existing science, however proud in its attained rationality, can disavow as its own progenitor. (_c_) Then there is also a speculative stage: a period of guessing, of making hypotheses, of framing ideas which later on are labeled and condemned as only ideas. There is a period of distinction and classification-making which later on is regarded as only mentally-gymnastic in character. And no science, however proud in its present security of experimental assurance, can disavow a scholastic ancestor. (_d_) Finally, there comes a period of fruitful interaction between the mere ideas and the mere facts: a period when observation is determined by experimental conditions depending upon the use of certain guiding conceptions; when reflection is directed and checked at every point by the use of experimental data, and by the necessity of finding such form for itself as will enable it to serve as premise in a deduction leading to evolution of new meanings, and ultimately to experimental inquiry, which brings to light new facts. In the emerging of a more orderly and significant region of fact, and of a more coherent and self-luminous system of meaning, we have the natural limit of evolution of the logic of a given science.