From all that has been said in the preceding paragraphs regarding the nature and causes of good and evil the errors of the Manichean system will be apparent. Its fundamental error is the conception of evil as a positive entity. Evil is not a positive entity but a privation. And this being so, its occurrence does not demand a positive efficient cause. It can be explained and accounted for by deficiency or failure in causes that are good in so far forth as they are operative, but which have not all the goodness their nature demands. And we have seen how this failure of created causes is permitted by the First Cause, and is not incompatible with His Infinite Goodness. Besides, the Manichean conception of an intrinsically evil cause, a cause that could produce only evil, is a contradiction in terms. The operation of an efficient cause must have a positive term: in so far as the term is positive it is good: and therefore its cause cannot have been totally evil, but must have been in some degree good. The crucial point in the whole debate is this, that we cannot conceive evil as a positive entity. By doing so we render reality unintelligible; we destroy the fundamental ground of any possible distinction between good and evil, thus rendering both alike inconceivable. Each is correlative to the other; we cannot understand the one without the other. If, therefore, goodness is an aspect of real being, and identical with reality, evil must be a negation of reality, and cannot be made intelligible otherwise. Finally, the Manichean conception of two Supreme, Self-Existent, Independent First Principles is obviously self-contradictory. As is shown in Natural Theology, Being that is absolutely Supreme, Self-Existent and Necessary, must by Its very nature be unique: there could not be two such Beings. CHAPTER VII. REALITY AND THE BEAUTIFUL. 53. THE CONCEPT OF THE BEAUTIFUL FROM THE STANDPOINT OF EXPERIENCE.—Truth and Goodness characterize reality as related to intellect and to will. Intimately connected with these notions is that of _the beautiful_,(193) which we must now briefly analyse. The fine arts have for their common object the expression of the beautiful; and the department of philosophy which studies these, the philosophy of the beautiful, is generally described as _Esthetics_.(194)