were wholly indifferent to the consequences of our presuppositions we would not postulate them, we would at least draw no conclusion from them.
1. James Clerk Maxwell (1831-1879), the noted physicist who was a professor at Cambridge, was a student of philosophy under William Hamilton, of whom he reminds us by his emphasis of the dynamic character of knowledge. He regards the mind as an organ, whose use may be valuable in itself, even though its practical significance consists in the results of its functional activity. The progress of the exact sciences rests upon the fact that we are able to elaborate ideas, in which all particular facts are represented and from which exact, mathematical conclusions can be deduced. In this respect the formation of number series has been singularly important: we are thus enabled to conceive physical variations after the analogy of the relations in the number series, according to the laws of numbers. This analogy can likewise be carried through most readily in its application to changes of position, and the natural science of the last three centuries has therefore aimed as far as possible to construe all phenomena as processes of motion. The theory of atoms rests upon a comprehensive analogy between the qualitative changes of matter and the movements of material points in space. As a matter of fact even geometry is really a theory of motion: a geometrical line is the path of a motion from one point to another.—The justification of the presuppositions lies in the fact that they lead to fruitful tasks and problems. Thus, e.g., the principle of the conservation of energy raises very definite questions in connection with every new phenomenon: whence does the energy here expended originate, and into what new form is it transformed, when the
