This division of Metaphysics, thoroughly sound in principle, and based on a sane and rational view of the relation between the special sciences and philosophy, has been almost entirely(24) supplanted in modern times by a division which, abstracting from the erroneous attitude that prompted it in the first instance, has much to recommend it from the standpoint of practical convenience of treatment. The modern division was introduced by Wolff (1679-1755), a German philosopher,—a disciple of Leibniz (1646-1716) and forerunner of Kant (1724-1804).(25) Influenced by the excessively deductive method of Leibniz’ philosophy, which he sought to systematize and to popularize, he wrongly conceived the metaphysical study of reality as something wholly apart and separate from the inductive investigation of this same reality in the positive sciences. It comprised the study of the most fundamental and essential principles of being, considered in themselves; and the deductive application of these principles to the three great domains of actual reality, the corporeal universe, the human soul, and God. The study of the first principles of being in themselves would constitute _General Metaphysics_, or _Ontology_ (ὄντος-λόγος). Their applications would constitute three great departments of _Special Metaphysics_: _Cosmology_, which he described as “transcendental” in opposition to the experimental physical sciences; _Psychology_, which he termed “rational” in opposition to the empirical biological sciences; and finally Natural Theology, which he entitled _Theodicy_ (Θεός-δίκη-δικαιόω), using a term invented by Leibniz for his essays in vindication of the wisdom and justice of Divine Providence notwithstanding the evils of the universe. “The spirit that animated this arrangement of the departments of metaphysics,” writes Mercier, “was unsound in theory and unfortunate in tendency. It stereotyped for centuries a disastrous divorce between philosophy and the sciences, a divorce that had its origin in circumstances peculiar to the intellectual atmosphere of the early eighteenth century. As a result of it there was soon no common language or understanding between scientists and philosophers. The terms which expressed the most fundamental ideas—matter, substance, movement, cause, force, energy, and such like—were taken in different senses in science and in philosophy. Hence misunderstandings, aggravated by a growing mutual distrust and hostility, until finally people came to believe that scientific and metaphysical preoccupations were incompatible if not positively opposed to each other.”(26) How very different from the disintegrating conception here criticized is the traditional Aristotelian and scholastic conception of the complementary functions of philosophy and the sciences in unifying human knowledge: a conception thus eloquently expressed by NEWMAN in his _Idea of a University_:—(27)