It is scarcely necessary to add that Monadism suffers besides from all the defects which we found in Pluralism. If the monad be made into a mere unit without internal variety, it ceases to be a thing with a definite nature at all; and if its unity is compatible with the variety of its states, there seems to be no special reason why the wealth of varied existence in the world should lead us to assume a plurality of independent principles as its ground. It has been pointed out that Leibnitz was apparently determined in favour of Monadism against Monism by the assumption that individual human selves are internally simple units and externally entirely exclusive of each other, an assumption we have already seen reason to reject. § 4. We seem driven, then, to reject the view that the ordered world of experience can be the expression of a plurality of ultimately distinct and heterogeneous principles. Because the world as known, or again as providing for the coherent realisation of practical purposes, is an orderly system, and on any other supposition coherent knowledge and consistent action are alike impossible, the world must for Metaphysics be regarded as the complete embodiment and expression of a single ultimate principle. We are thus committed to some form of theory of the type generally known as Monism. The _name_ Monism we may perhaps be allowed to avoid, as it has gathered about it associations which are apt to mislead. Among the doctrines most frequently spoken of as monistic are some which treat the apparent variety and multiplicity of existence as purely illusory. Again, the name has of late been widely used as the self-chosen designation of the doctrine according to which “mind” and “matter” are alike “aspects” or “manifestations” of a third principle which is neither material nor mental. It should already be clear that the doctrine indicated by our previous discussions differs widely from both these types of Monism. We have insisted that the source of fallacy in Pluralism and Monadism was one-sided emphasis upon one term in the antithesis of the Many and the One to neglect of the other, and we have no intention of repeating the mistake for ourselves. Also, we have already come to the conclusion that Reality, whatever its detailed structure, is mental in its general character; we can have nothing therefore to do with a “neutral” or “agnostic” Monism. Our detailed theory of the relation between the unity of the world and its multiplicity must do equal justice to both, and it must be consistent with our previous recognition of the experiential nature of the real.