involved in its coming into being. Suppose the problem to be the nature of water. By 'nature' we mean no inner metaphysical essence; its 'nature' is found only by experiencing it. By nature, in science, we mean a knowledge for purposes of intellectual and practical control. Now, water simply as a given fact resists indefinitely and obstinately any direct mode of approach. No amount of scrutiny, no amount of observation of it as given, yields analytic comprehension. Observation but complicates the problem by revealing unsuspected qualities that require additional explanation.
What experimentation does is to let us see into water in the process of making. Through generating water we single out the precise and sole conditions which have to be fulfilled that water may present itself as an experienced fact. If this case be typical, then the experimental method is entitled to rank as genetic method; it is concerned with the manner or process by which anything comes into experienced existence.
Even those willing to admit this, would probably refuse to go further, and hold that the experimental method is in a true sense an historical or evolutionary method. A consideration of the reasons for refusing to take this step will throw light upon the problem. A strictly historical series is unique, not only in any one of its constituent members, but in the particular place it occupies in the series. Its own context is indispensable to its historic character. Now, in the physical world, with which the experimental sciences deal, sets or pairs of terms are not thus limited to any particular temporal part of the series. They occur and recur; and suffer no change of quality by reason of dislocation from a given context. Water is made over and over again, and, so to speak, at any date in the cosmic series. This deprives any account of it of genuinely historic quality.
Another consideration which gives us pause is that the main interest in physical science does not concern the individual case, but certain further and more general results which at once emerge and absorb attention. We have the common saying that the physical sciences are not interested in individual cases as such, but only in general laws. The particular case is taken simply as
