We may perhaps work out our theory in detail as follows. The world for knowledge must, we have seen, be an orderly whole or system. To be a system at all, it must be the development or expression in detail of a single principle. Therefore it must most certainly be one; it cannot be a medley of independent elements which somehow luckily happen to form a coherent collection. But again, because it is a system, it cannot be a mere unit; it must be the expression of a single principle in and through a multiplicity of terms or constituents. Not only must it be both one and many, but it must be many precisely because it is truly one, and one because it is truly many.[59] Further, we must add that because the world-system is a perfectly systematic whole, not only is multiplicity in general necessary to its unity, but each particular element in the multiplicity is necessitated or logically implied by the character of the unity. In a complete system no single member can be missing or be other than it is without the fundamental law of construction of the whole being changed. Also, we may incidentally observe that in a complete system the number of distinct terms may be actually endless, while the law of construction is perfectly determinate. To think of the world as a single systematic unity, then, means to think of it as the manifestation in a possibly infinite multiplicity of detail of one perfectly determinate principle. And, of course, what we have called the individual elements of the multiplicity may on inspection themselves turn out to be systems of infinite complexity determined by a law of construction derived in a determinate way from that of the complete system, and so on literally _ad infinitum_. Thus the unity of ultimate principle we demand for Reality in no way excludes its possession of a wealth of detail infinitely infinite.