The interest to us in this extraordinary man--who died at Hanover, 1716, in the midst of his labors and projects--turns mainly on his speculative philosophy. It was only as an incidental pursuit that he occupied himself with metaphysic; yet no philosopher since Aristotle-- with whom, though claiming to be more Platonic than Aristotelian, he has much in common--has furnished more luminous hints to the elucidation of metaphysical problems. The problems he attempted were those 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_ [14], 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. [Footnote 14: That is, as a discipline of the faculties,--the chief benefit to be derived from any kind of metaphysical study.]