Necessary truths are those the contrary of which is impossible; accidental truths, those of which the contrary is impossible only under certain conditions. Now, revelation could not contradict necessary truths; but it may appear to contradict those which are accidental. Geometrical truths are necessary; and therefore revelation could not oppose them; but as accidental truths refer to the changes of natural things, it follows that these may be apparently contradicted by revelation; though if we search minutely, we shall at last be able to lift the veil from the contradictions. _Fourth._ Revelation cannot command anything contrary to the laws of the nature of existence and of the mind, for whatever is opposed to the laws of nature is equally opposed to those of reason. _Fifth._ When it can be proved that he who declares that he has received a divine revelation has arrived at his knowledge by the natural use of his mental powers, then his declaration cannot be considered true. _Sixth._ In a revelation all things ought to be expressed in such words, or by such signs, that he who is the object of it can clearly recognize the divine action. For God knows all possible symbolical means of knowledge, and does nothing without a purpose. These views Wolff taught from his university-chair in Halle, and disseminated throughout the land in publications under various titles. He aimed to reach not only the young theologians and all who were likely to wield a great public influence, but to so popularize his system that the unthinking masses might become his followers. He succeeded. Even Roman Catholics embraced his tenets, and he was accustomed to say, with evident satisfaction, that his text-books were used at Ingolstadt, Vienna, and Rome. The glaring defect of his philosophy was his application of the formal logical process to theology. He reduced the examination of truth to a purely mechanical operation. The effect was soon seen. When his students began to fill the pulpits the people heard cold and stately logic, extended definitions, and frequent mathematical phrases. Think of the clergy feeding their flocks on such food as the following: "_God--a being who supports all the world at one time_;" "_Preestablished harmony--the eternal union of things_;" "_Ratio sufficiens--the sufficient ground_;" with many other arid definitions of the same class. One preacher, in explaining the eighth chapter of Matthew, thought it necessary, when noticing the fact of Jesus descending the mountain, to define the term mountain by declaring it to be "a very elevated place;" and, when discoursing on Jesus stretching forth his hand and touching the leper, to affirm that "the hand is one of the members of the body." It is astonishing how quickly the popular principles and teachings of the followers of Wolff began to supplant Pietism. In the university and the pulpit there were sad and numerous evidences of decline. Perhaps no system of philosophy has ever