We may sum up what has been said about matter as an element in the monad, or as a metaphysical principle, as follows: The existence of matter is not only not opposed to the fundamental ideas of Leibniz, but is a necessary deduction from them. It is a necessity of the principle of continuity; for this requires an infinity of monads, alike indeed in the universal law of their being, but unlike, each to each, in the specific coloring or manifestation of this law. The principle of organic unity requires that there be as many real beings as possible participating in and contributing to it. It is necessary, again, in order that there may be reciprocal influence or connection among the monads. Were it not for the material element in the monad, each would be a God; if each were thus infinite and absolute, there would be so many principles wholly independent and isolated. The principle of harmony would be violated. So much for the necessity of the material factor. As to its nature, it is a principle of passivity; that is, of ideal receptivity, of conformity to a law apparently not self-imposed, but externally laid down. This makes matter equivalent to a phenomenon; that is to say, to the having of confused, imperfect, inadequate ideas. To say that matter is correlative to confused ideas is to say that there is no recognition of its relation to self or to spirit. As Leibniz sometimes puts it, since there is an infinity of beings in the universe, each one of which exercises an ideal influence upon every other one of the series, it is impossible that this other one should realize their full meaning; they appear only as confused ideas, or as matter. To use language which Leibniz indeed does not employ, but which seems to convey his thought, the spirit, not seeing them as they really are, does not _find_ itself in them. But matter is thus not only the confused manifestation or phenomenon of spirit, it is also its potentiality. Passivity is always relative. It does not mean complete lack of activity; that, as Leibniz says, is nothingness, and matter is not a form of nothingness. Leibniz even speaks of it as passive _power_. That is to say, there is an undeveloped or incomplete activity in what appears as matter, and this may be,--if we admit an infinity of time,--must be developed. When developed it manifests itself as it really is, as spirit. Confused ideas, as Leibniz takes pains to state, are not a genus of ideas antithetical to distinct; they differ only in degree or grade. They are on their way to become distinct, or else they are distinct ideas which have fallen back into an "involved" state of being. Matter, therefore, is not absolutely opposed to spirit,--on the one hand because it is the manifestation, the phenomenon, of spirit; on the other, because it is the potentiality of spirit, capable of sometime realizing the whole activity implied in it, but now latent.