a very slow one. We may well despair of ever reducing the phenomena of nature to such simple laws as that of gravitation. It may be that our hope of doing anything of the kind has received a great set-back by the iconoclastic way in which the discovery of radio-activity has shaken to its foundations what, ten years ago, were supposed to be fundamental principles at play in the material world.
But we still find the process of integration to be going on as our knowledge advances. The discovery of principles more or less general which, being mastered, will enable a single mind to grasp a continually widening field of research is constantly going forward. It is true that we are not to expect the revival of the medieval professor of all science; but we may look for a class of widely educated men who, if not masters of the details of any one science, will yet have at command so comprehensive a grasp of great principles as to be able to form an intelligent judgment on those questions of science and learning which are of the widest human interest, and which most influence the progress of the world. It is not necessary to burden the memory with details of the forms and habits of every species of animal or vegetable in order to form an intelligent idea of the general laws of life and of the conditions of its propagation. The intelligent reader of history may condense its lessons into small space, even though he fails to remember details of dynasties, battles or treaties.
This process is facilitated by the natural tendency of every science, when pursued by the best methods, to become more precise in the expression of its laws, and thus to bring mathematical conceptions to the aid of its investigators. When we have not only assigned a name to an object of study, but have made measurement of its size, or of the intensity of any ascertained properties it exhibits, we have taken a great step toward giving precision to our results, and making them comprehensible to a wider body of investigators.
With these preliminary considerations we see what interest attaches to the enterprise of bringing all the sciences together for a week's discussion of their problems and relations. That this is no easy task will be conceded, indeed serious doubts and great incredulity as to its practicality were expressed. But the promoters of the plan have gone on, confident that the farther it was pursued and the better it was understood, the more hopeful the view that would be taken of its outcome. The central theme around which the whole is grouped is the unity of science. This theme is carried through from the center into details which shall include every branch of learning. With it is associated the discussion of the conceptions, progress, relations and problems of the various sciences. The details of the plan as finally worked out are round in the programs of the congress, which so many readers of The Popular Science Monthly have probably seen, that only a