SUBJECT CLASSIFICATION.
5. General Principles. —Like every other system of exact classification, this one is arranged, as regards its main divisions, in a logical order, or at any rate, according to a progression for which reasons, weak or strong, can be advanced. Its basis is a recognition of the fact that every science and art springs from some definite source, and need not, therefore, be arbitrarily grouped in alphabetical, chronological or purely artificial divisions, because tradition or custom has apparently sanctioned such a usage. The divisions seen in most classifications in vogue —Fine Arts, Useful Arts and Science, are examples of the arbitrary separation of closely related subjects, which in the past have become conventional, and it may seem heretical even at this late time to propose a more intimate union between exact and applied science. Nevertheless, this is what has been attempted here, and those who use the scheme will find many departures from established convention which may at first sight appear a little drastic. The alliance of Architecture and Building, Acoustics and Music, Physical
Electricity and Electrical Engineering, and other groupings of a similar kind are departures from the convention that there exists a clear difference between theory and practice, pure and applied science, and so on, which renders their amalgamation undesirable. The old distinction between theoretical and applied science is gradually disappearing from all modern text-books, and it is obvious that, as the systematisation of science and its teaching improve, the separation between physical basis and practical application, hitherto maintained, will no longer be insisted upon. In th's scheme of Subject Classification every class is arranged in a systematic order of scientific progression, as far as it seemed possible to maintain it ; while applications directly derived from a science or other theoretical base, have been placed with that science or base. Composite applications of theory have been placed with the nearest related group which would
6. The Order of the Main Classes. — ^The reasons which determined the adopticjn of a certain sequence of classes in this system may be briefly set forth here, instead of any argument or attempt to justify the order. The battle which has raged, and is still raging, among scientists, as to the best and most desirable order in which to arrange the great branches of human knowledge in order to produce a " hierarchy," must deter a non- scientific classifier from arguing on such a complicated and difficult topic. It will, therefore, suffice, if I briefly describe the main classes in their order and give reasons why they were assigned to the places they occupy.
A Generalia. —The divisions of this main class comprise most of the rules, methods and factors which are of general application, and which qualify or pervade every branch of science, industry or human study. They are universal and pervasive, and cannot be logically assigned to any other single main class as peculiar or germane to it.
II
take them without strain, and, as a general rule, all through the classifica- tion the endeavour has been to maintain a scheme of one subject, one place.