We see, then, that two of the three possible theories of things contain the elements of their own destruction: when carefully analyzed, both these theories are found to present inherent contradictions. On this account the third, or only alternative theory, comes to us with a large antecedent presumption in its favour. For it comes to us, as it were, on a clear field, or with the negative advantage of having no logical rivals to contend with. The other two suggestions having been weighed in the balance and found wanting, we are free to look to the new-comer as quite unopposed. This new-comer must, indeed, be interrogated as carefully as his predecessors, and, like them, must be judged upon his own merits. But as he constitutes our last possible hope of solving the question which he professes himself able to solve, the absolute failure of his predecessors entitles him to a patient hearing. By the method of exclusion his voice is now the only voice that remains to be heard, and unless it can speak to better purpose than the others, we shall have no alternative but to abandon the facts as inexplicable, or to confess that it is necessarily impossible for the human mind ever to arrive at any theory of things. Before proceeding to state or to examine this third and last of the suggested theories, it is desirable--in order still further to define its _status a priori_--that I should exhibit the reason why the two other suggestions have necessarily failed. For to my mind it is perfectly obvious that this reason is to be found, and found only, in the fact that they are both dualistic. The inherent, the fatal, and the closely similar difficulties which attach to both the dualistic theories, attach to them merely because they _are_ dualistic. The 'nonsense' of each of them is really identical, and arises only because they both make the same irrational attempt to find more in the effect than they have put into the cause. In other words, both the dualistic theories suppose that the physical chains of causation is complete within itself, and that the mental chain is also complete within itself: yet they both proceed to the contradiction that one of these chains is able to allow some of its causal influence to escape, as it were, in order to constitute the other chain. It makes no difference, in point of logic, whether such an escape is supposed to take place from the physical chain (materialism) or from the mental chain (spiritualism): in either case the fundamental principle of causality is alike impugned--the principle, that is, of there being an equivalency between cause and effect, such that you cannot get more out of your effect than you have put into your cause. Both these dualistic theories, although they take opposite views as to which of the two chains of causation is the cause of the other, nevertheless agree in supposing that there _are_ two chains of causation, and that one of them _does_ act causally upon