which concern the most inscrutable, but, to the genuine metaphysician, most fascinating of all topics, the nature of substance, matter and spirit, absolute being,—in a word, Ontology. This department of metaphysic, the most interesting, and, agonistically,[1] the most important branch of that study, has been deliberately, purposely, and, with one or two exceptions, uniformly avoided by the English metaphysicians so-called, with Locke at their head, and equally by their Scottish successors, until the recent "Institutes" of the witty Professor of St. Andrew's. Locke's "Essay concerning the Human Understanding," a century and a half ago, diverted the English mind from metaphysic proper into what is commonly called Psychology, but ought, of right, to be termed Noölogy, or "Philosophy of the Human Mind," as Dugald Stewart entitled his treatise. This is the study which has usually taken the place of metaphysic at Cambridge and other colleges,—the science that professes to show "how ideas enter the mind"; which, considering the rareness of the occurrence with the mass of mankind, we cannot regard as a very practical inquiry. We well remember our disappointment, when, at the usual stage in the college curriculum, we were promised "metaphysics" and were set to grind in Stewart's profitless mill, where so few problems of either practical or theoretical importance are brought to the hopper, and where, in fact, the object is rather to show how the upper mill-stone revolves upon the nether, (reflection upon sensation,) and how the grist is conveyed to the feeder, than to realize actual metaphysical flour.
Locke's reason for repudiating ontology is the alleged impossibility of arriving at truth in that pursuit,—"of finding satisfaction in a quiet and sure possession of truths that most concern us, whilst we let loose our thoughts into the vast ocean of being."[2] Unfortunately, however, as Kant has shown, the results of noölogical inquiry are just as questionable as those of ontology, whilst the topics on which it is employed are of far inferior moment. If, as Locke intimates, we can know nothing of being without first analyzing the understanding, it is equally sure that we can know nothing of the understanding except in union with and in action on being. And excepting his own fundamental position concerning the sensuous origin of our ideas,—to which few, since Kant, will assent,— there is hardly a theorem, in all the writings of this school, of prime and vital significance. The school is tartly, but aptly, characterized by Professor Ferrier: "Would people inquire directly into the laws of thought and of knowledge by merely looking to knowledge or to thought itself, without attending to what is known or what is thought of? Psychology usually goes to work in this abstract fashion; but such a mode of procedure is hopeless,—as hopeless as the analogous instance by which the wits of old were wont to typify any particularly fruitless undertaking,—namely, the operation of milking a he-goat into a sieve. No milk comes, in the first place, and even that the sieve will not retain! There is a loss of nothing twice over. Like the man milking, the inquirer obtains no milk in the first place; and, in the second place, he loses it, like the man holding the sieve. . . . Our Scottish philosophy, in particular, has presented a spectacle of this description. Reid obtained no result, owing to the abstract nature of his inquiry, and the nothingness of his system has escaped through all the sieves of his successors."[3]
Leibnitz's metaphysical speculations are scattered through a wide variety of writings, many of which are letters to his contemporaries. These Professor Erdmann has incorporated in his edition of the Philosophical Works. Beside these we may mention, as particularly deserving of notice, the "Meditationes de Cognitione, Veritate et Ideis", the "Systeme Nouveau de
