In its development this theory was made to be of the greatest help in the explanation of many other difficulties with regard to living as well as non-living things in their hands. The theory has its difficulties, but they are less than those of any other theory of the constitution of matter, and it has been accepted by more philosophic thinkers since the Thirteenth Century than any other doctrine of similar nature. It may be said that it was reached only by deduction and not by experimental observation. Such an expression, {41} however, instead of being really an objection is rather a demonstration of the fact that great truths may be reached by deduction yet only demonstrated by inductive methods many centuries later. Of course it may well be said even after all these communities of interest between the medieval and the modern teaching of the general principles of science has been pointed out, that the universities of the Middle Ages did not present the subjects under discussion in a practical way, and their teaching was not likely to lead to directly beneficial results in applied science. It might well he responded to this, that it is not the function of a university to teach applications of science but only the great principles, the broad generalizations that underlie scientific thinking, leaving details to be filled in in whatever form of practical work the man may take up. Very few of those, however, who talk about the purely speculative character of medieval teaching have manifestly ever made it their business to know anything about the actual facts of old-time university teaching by definite knowledge, but have rather allowed themselves to be guided by speculation and by inadequate second-hand authorities, whose dicta they have never taken the trouble to substantiate by a glance at contemporary authorities on medieval matters.