Now, it follows from this that every true science must be a domain of force; that each science must preside over some one of these various forces, and that any field of knowledge which has not been brought under the operation of some natural force is not yet a science in the proper sense of that word. The mere accumulation of facts does not constitute a science, but a successful classification of the facts recognizes the law underlying them and is, in so far, scientific. In fact, classification is always the initial step in the establishment of a science, and the more recondite workings of the force over which it presides are discovered later.