ucts, but will even tend to make the conceptions of products wrong. The analytical habit of mind has to be supplemented by the synthetical habit of mind. Seen in its proper place, analysis has for its chief function to prepare the way for synthesis; and, to keep a due mental balance, there must be not only a recognition of the truth that synthesis is the end to which analysis is the means, but there must also be a practice of synthesis along with a practice of analysis.
All the Concrete Sciences familiarize the mind with certain cardinal conceptions which the Abstract and Abstract-Concrete Sciences do not yield—the conceptions of continuity, complexity, and contingency. The simplest of the Concrete Sciences, Astronomy and Geology, yield the idea of continuity with great distinctness. I do not mean continuity of existence merely; I mean continuity of causation: the unceasing production of effect—the never-ending work of every force. On the mind of the astronomer there is vividly impressed the idea that any one planet which has been by so much swerved out of its course by another planet, or by a combination of others, will through all future time follow a route different from that it would have followed but for the perturbation; and he recognizes its reaction upon the perturbing planet or planets, as similarly having effects which, while ever being complicated and ever slowly diffused, will never be lost during the immeasurable periods to come. So, too, the geologist sees in each change wrought on the earth's crust, by igneous or aqueous action, a new factor that goes on perpetually modifying all subsequent changes. An upheaved portion of sea-bottom alters the courses of ocean-currents, modifies the climates of adjacent lands, affects their rainfalls and prevailing winds, their denudations and the deposits round their coasts, their floras and faunas; and these effects severally become causes that act unceasingly in ever-multiplying ways. Always there is traceable the persistent working of each force, and the progressive complication of the results through succeeding geologic epochs.
These conceptions, not yielded at all by the Abstract and Abstract-Concrete Sciences, and yielded by the inorganic Concrete Sciences in ways which, though unquestionable, do not arrest attention, are yielded in clear and striking ways by the organic Concrete Sciences—the sciences that deal with living things. Every organism, if we choose to read the lessons it gives us, shows continuity of causation and complexity of causation. The ordinary facts of inheritance illustrate continuity of causation—very conspicuously where varieties so distinct as negro and white are united, and where traces of the negro come out generation after generation; and still better among domestic animals, where traits of remote ancestry show the persistent working of causes which date far back. Organic phenomena make us familiar with complexity of causation, both by showing the coöperation of many antecedents to each consequent, and by snowing the multiplicity of results which each influence works out. If we observe how a given weight