Nothing is more curious in the history of recent science than the continual and irresistible growth which it records in the importance of electrical phenomena. All others tend to become merged in them; the most varied data of experience claim to be translated into electrical terminology. They are not, assuredly, rendered more intelligible by the process, but it at any rate abolishes the confusion incidental to multitudinous points of view. Thus, in the last resort, we find electrical forces (if they may be so designated) swaying the world. What they essentially consist in, we cannot tell; the utmost that may reasonably be hoped for is to arrive at a clear conception of modes of action reduced to antagonistic stresses, by which the play and counterplay of the universe may be kept up. And to this extent we find it possible to understand how electricity works the ethereal machinery. It is strongly dualistic. The nearer we get to the foundations of nature, the more sharply positive and negative charges appear to be differentiated. The opinion is nevertheless held by some inquirers that negative electricity is the only substantive kind, and that its complement is ordinary matter deprived of some of its negative particles. This, in fact, revives Franklin's 'one fluid theory,' only with the substitution of negative for positive electricity as the active principle.[72] But we are met by the doubt whether 'ordinary matter' can be said to exist in and by itself. If it do, the mode of its existence becomes more and more baffling to comprehension, as the association of mass with charge makes its way into the foreground of thought.[73] Moreover, a charge is, or produces, a 'state of the ether' (to use the unsatisfactory current phrase); and the ether being capable of opposite distortions, the effects upon it of opposite charges are contrary and similar, though perhaps not equivalent; whence the 'two fluid theory' obtains a _primâ facie_ recommendation as the simplest, though a crude interpretation of electrical phenomena. These are ubiquitous; destitute though we are of sense-organs for their perception, we still indirectly recognise their presence on every side. If the unification of the forces in nature be attainable, the unifying formula will doubtless be derived from them. Electricity is the _mot de l'énigme_; yet it is itself the most inscrutable of enigmas. FOOTNOTES: [Footnote 62: Lorentz, _Proceedings Amsterdam Academy_, 1900, p. 565.] [Footnote 63: Sir W. Thomson, _Philosophical Magazine_, vol. xlv., fourth series, 1873. Many hints have been taken, in what is above written, from this valuable paper.] [Footnote 64: Sir W. Thomson (Lord Kelvin), _loc. cit._, p. 323.] [Footnote 65: _Electricity and Matter_, p. 159.] [Footnote 66: _Loc. cit._, p. 331.] [Footnote 67: _Traité de Mécanique Céleste_, tome. iv., p. 495.] [Footnote 68: _Electricity and Matter_, p. 160.] [Footnote 69: _Proceedings Amsterdam Academy of Sciences_, 1900, p. 559.]