its individuality to its motion.[1] But on either hypothesis, the nearer we draw to the ultimate elements of matter the better we note the vanishing of that discontinuity which our senses perceived on the surface. Psychological analysis has already revealed to us that this discontinuity is relative to our needs: every philosophy of nature ends by finding it incompatible with the general properties of matter.
In truth, vortices and lines of force are never, to the mind of the physicist, more than convenient figures for illustrating his calculations. But philosophy is bound to ask why these symbols are more convenient than others, and why they permit of further advance. Could we, working with them, get back to experience, if the notions to which they correspond did not at least point out the direction in which we may seek for a representation of the real? Now the direction which they indicate is obvious; they show us, pervading concrete extensity, modifications, perturbations, changes of tension or of energy, and nothing else. It is by this, above all, that they tend to unite with the purely psychological analysis of motion which we considered to begin with, an analysis which presented it to us not as a mere change of relation between objects to which it was, as it
- ↑ Thomson, On Vortex Atoms (Proc. of the Roy. Soc. of Edin., 1867). An hypothesis of the same nature had been put forward by Graham, On the Molecular Mobility of Gases (Proc. of the Roy. Soc., 1863, p. 621 et seq.).
