Page:An Enquiry Concerning the Principles of Natural Knowledge.djvu/39

equations be modified, the motion of the ether does not enter into experience. Accordingly Lorentz assumes a stagnant ether: that is to say, an ether with no motion, which is simply the ultimate entity of which the vectors $(F_{\alpha },G_{\alpha },H_{\alpha })$ and $(L_{\alpha },M_{\alpha },N_{\alpha })$ express properties. Such an ether has certainly a very shadowy existence; and yet we cannot assume that it moves, merely for the sake of giving it something to do.

6.3 The ultimate facts contemplated in Maxwell’s equations are the occurrences of $\rho _{\alpha }$ (the volume-density of the charge), $(u_{\alpha },v_{\alpha },w_{\alpha })$, $(F_{\alpha },G_{\alpha },H_{\alpha })$ and $(L_{\alpha },M_{\alpha },N_{\alpha })$ at the space-time points in the neighbourhood surround- ing the space-time point $(x_{\alpha },y_{\alpha },z_{\alpha },t_{\alpha })$. But this is merely to say that the ultimate facts contemplated by Maxwell’s equations are certain events which are occurring throughout all space. The material called ether is merely the outcome of a metaphysical craving. The continuity of nature is the continuity of events; and the doctrine of transmission should be construed as a doctrine of the coextensiveness of events with space and time and of their reciprocal interaction. In this sense an ether can be admitted; but, in view of the existing implication of the term, clearness is gained by a distinction of phraseology. We shall term the traditional ether an ‘ether of material’ or a ‘material ether,’ and shall employ the term ‘ether of events’ to express the assumption of this enquiry, which may be loosely stated as being ‘that something is going on everywhere and always.’ It is our purpose to express accurately the relations between these events so far as they are disclosed by our perceptual experience, and in particular to consider those relations from which the essential concepts of Time, Space, and persistent material are