Diffused throughout matter, electricity is ever active; but it must be remembered that although it is evidently a necessary agent in all the operations of nature, that it is not the agent to which everything unknown is to be referred. Doubtless the influence of this force is more extensive than we have yet discovered; but that is an indolent philosophy which refers, without examination, every mysterious phenomenon to the influence of electricity. The question, what is electricity? has ever perplexed, and still continues to agitate, the world of science. While one set of experimentalists have endeavoured to explain the phenomena they have witnessed, upon the theory that electricity is a peculiar subtile fluid pervading matter, and possessing singular powers of attraction and repulsion, another party find themselves compelled to regard the phenomena as giving evidence of the action of two fluids which are always in opposite states; while again, electricity has been considered by others as, like the attraction of gravitation, a mere property of matter.[136] Certain it is, that in the manifestations of electrical phenomena we have, as it appears, the evidence of two conditions of force; but of the states of _positive_ or _negative_, of _vitreous_ or _resinous_ electricity, we have a familiar explanation in the assumption of some current flowing into or out of the material body,--of some principle which is ever active in maintaining its equilibrium, which, consequently, must act in two directions, and always exhibit that duality which is a striking characteristic of this subtile agent. It is a curious, and it should be an instructive fact, that each of the three theories of electricity is capable of proof, and has, indeed, been most ably supported by the rigorous analysis of mathematics. When we remember that some of the most enlightened investigators of this and the past age have severally maintained, in the most able manner, these dissimilar views, we should hesitate before we pronounce an opinion upon the cause or causes of the very complicated phenomena of electrical force.