SOCIOLOGICAL CONSTRUCTION LINES 2Q
tific conclusion that these conditions are the "causes" of such phenomena.
Description and explanation, so far as explanation is possible to science, are essentially alike as well as essentially different. Each consists in thinking phenomena together in relations in which they exist together. The difference between explana- tion and other description is that in mere description we may think together whatever may be observed together, and share our interest together; while in explaining a thing we think it together with certain other things, namely, such things as are alleged as causes. All our knowledge consists in think- ing phenomena together in the relations in which they exist together. This is true of the whole range of understand- ing, from sense-perception to philosophy. The isolated sense- impression is meaningless. The splotch of variegated light falling on the newborn baby's eye has no meaning for his mind. That light may be reflected from the vine that clambers past the window, but not a leaf upon the vine can be perceived until the present sensation is put together with a variety of other present or remembered sensations that combine to give the notion "leaf out there." Our knowledge of a phenomenon extends as we think more phenomena together with it; as they exist or have existed together with it; as we know more about it. The advancement of knowledge consists a little in seeing more things, and a great deal in becoming aware of more relations between things relations of time, relations of space, and especially the relations which we name causal.
A child in a museum, looking at a chipped flint or a bit of corroded bronze, sees as much of the things as the paleontolo- gist, but he knows less about them, because the vision of these things does not conjure up in his mind the ideas of other things which are known or believed to have been related to every object of the class represented by the ancient arrow-head or sword. There are three phases of knowledge. The first and most elementary is seeing things, present results, static phenomena; the two other and higher phases are the observation of changes, differences, and resemblances till, first, we can think of the resem-
