4o THE POPULAR SCIENCE MONTHLY 



for the practical man is nothing if not outspoken in his dislike of hair- 

 splitting 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 terri- 

 tory 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 com- 

 plete, 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, off- 

 hand, 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, never- 

 theless, together with the principle of classification which it implies, 

 must now be discarded ; the sciences can not be looked upon as depart- 

 ments of knowledge, adjoining and mutually exclusive, each one cover- 

 ing 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 



