against a vague background of not-x; we need the special and definite antithetic conception to x within the particular "Universe of Thought" to which x properly belongs. And often we have to investigate a class of things as forming a part of more than one Universe of Thought, and contrast it with not-x in each. As, for instance, we may clear up our conception of "black sheep" by contrasting it, first, with "sheep that are not black"; secondly, with "black objects that are not sheep"; and so on. The Differential Calculus, however, shows that the mind is feeling after even a more definite mode of contrast than that indicated above. We cannot truly know the Law which governs an organic group of phenomena, unless we allow ourselves to conceive the idea of a Singular Solution of that Law, i.e., an individual which is constant in some relations as to which the other individuals are variable, and variable in some relations as to which the others are constant.
Now the so-called Messianic Seers are persons in whom is developed to a high degree the tendency to study ordinary human beings by the method of contrast with an Ideal Man, a sort of Singular Solution of Humanity; of whom they speak as constant in those relations to the Unseen in which we are variable, and fluent in those relations to the visible as to which each of us has his fixed prejudices. This Ideal Man, they assert, is the indispensable Mediator between them and any true knowledge of Humanity. When they have jumped to the conclusion that their need of conceiving an Ideal Man is any proof of the actual existence of such an Ideal, visible or Invisible, they err, of course. But, nevertheless, these Messianic Seers are neither
