for the practical man is nothing if not outspoken in his dislike of hairsplitting distinctions and formal definitions. Let it then he said, at once, that there shall be no formal definition in the present paper, and that there shall be as many loose ends left as the most matter-of-fact common sense can desire. The distinction to be drawn is, in truth, elementary, and the drawing will here be done in the grossest way.
What follows, therefore, is an attempt at an eirenicon; and it begins at the beginning, with the question—What do we mean by science?
I
We are still told, in text-books and scientific addresses, that the various sciences represent various departments of knowledge. The territory of science, that is to say, is conceived of as parcelled out among the separate sciences, very much as a continent is mapped out into a number of adjoining countries. If the tale of the sciences were complete, the whole map would be variously colored; since, however, there are "gaps" in our knowledge, the map shows blank spaces, unexplored regions to which the methods of science have not yet attained. "The gaps are being filled; we are no longer isolated, but are working side by side on adjacent areas which are inseparably connected;" so said the president of the recent Medical Congress; and the figure was probably as familiar to his hearers as it fell naturally from his own lips.
A figure of this sort, however uncritically it may afterwards be employed, is always suggested in the first instance by some aspect of the facts; and in the present case the suggestion is not only obvious, but is also continually renewed. Few of us would hesitate to say, offhand, that the "tree" belongs to the province of botany, and the "inclined plane" to the province of physics. The things that we find in our surroundings fall, as we say, into groups, as subject-matter of this or that science; and the sorting or classifying of things, which is perhaps the earliest form of man's intellectual mastery of his world, still suffices for practical purposes and may, as our quotation shows, prove to be sufficient also in scientific contexts. That figure, nevertheless, together with the principle of classification which it implies, must now be discarded; the sciences can not be looked upon as departments of knowledge, adjoining and mutually exclusive, each one covering and exhausting a certain tract or region of experience, and each one concerned with a separate kind of subject-matter. The tree, we said, is placed by our ordinary thinking in the province of botany; yet this same tree may be considered from the points of view of taxonomy, ecology, distribution, morphology, physiology; it may be discussed by chemistry, or by general biology; and finally as look and feel it belongs, with all the looks and feels, to psychology. The inclined plane is in a like ambiguous position. These are, no doubt, trivial examples; but
