Page:Popular Science Monthly Volume 79.djvu/171

Rh does not destroy the specific identity of a substance. To a change which does destroy this specific identity we apply the term physical. This is, of course, a narrow use of the term, hut it is in accordance with past usage. Chemical phenomena are, then, the phenomena produced by chemical forces, and physical changes are those produced by molecular and molar forces. Chemical phenomena are first in order of time. "In the beginning" were atoms, atomic forces, atomic changes, chemism.

The second order of phenomena are the physical. They include the movements of molecules and masses from the invisible compounds of atoms to the great aggregates of matter in suns and stars. They are the natural outgrowth of chemical changes. Cooperating with the chemical forces the physical produced organic matter, protoplasm, and thus initiated the third great natural group of phenomena, the biological. Biological phenomena, which are the manifestation of the biotic forces, include, of course, the whole range of phenomena between inorganic nature and the origination of mind. Mind, we must assume, was also the creation of the preexisting forces, and the manifestations of mind, or psychic phenomena, constituted the fourth great division of phenomena. Finally, beginning with the origin of social groups, we have the constantly extending field of phenomena known as social, a direct manifestation of the social forces.

We have now presented a classification of forces and phenomena based on their genetic relationships. This, it will be observed, is equivalent to the classification of possible knowledge concerning concrete phenomena. It is thus a classification of the sciences. For a science is a study, or the classified knowledge resulting from the study, of a definite field of phenomena occurring in natural sequence as a result of a particular set of forces. Our classification of forces and of phenomena in their genetic order is, then, in reality a serial or genetic classification of the subject matter of the sciences. "Sciences," says Ward, "in so far as they can be grouped at all, simply represent the natural groups of phenomena, and to determine the natural order in which phenomena are related to one another as indicated by their respective antecedence and sequence in the march of evolving forces, is to determine the natural order in which the sciences stand to one another." The respective fields of forces and phenomena as already classified, then, imply corresponding sciences. There are five such fields, namely, chemical, physical, biological, psychological and sociological. Hence there are five great sciences: chemistry, physics, biology, psychology and sociology; and unless phenomena do not arise in the order stated above, this is a classification of the sciences which implies their genetic relationships and their relations of dependence. It is the order, too, of increasing