remnant of the conception of intelligence as purely particular and finite will catch him tripping. On the other hand, we realize much better than those who have behind them a Leibniz and a Kant, rather than a Locke and a Hume, the meaning and the thorough-going necessity of the universality of intelligence. Idealism must be in some ways arbitrary and superficial to him who has not had a pretty complete course of empiricism.
Leibniz seems to have been impressed with the Essay on the Human Understanding at its first appearance. As early as 1696 we find him writing a few pages of comment upon the book. Compared with his later critique, these early “reflections” seem colorless, and give the impression that Leibniz desired to minimize his differences from Locke rather than to set them forth in relief. Comparatively slight as were his expressions of dissent, they appear to have stung Locke when they reached him. Meantime Locke’s book was translated into French, and made its way to a wider circle of readers. This seems to have suggested to Leibniz the advisability of pursuing his comments somewhat further; and in the summer of 1703 he produced the work which now occupies us. A letter which Leibniz wrote at about this time is worth quoting at large for the light which it throws upon the man, as well as for suggesting the chief points in which he differed from Locke. Leibniz writes:—
“I have forgotten to tell you that my comments upon the work of Locke are nearly done. As he has spoken in a chapter of his second book about freedom, he has given me an opportunity to discuss that; and I hope that I may have done it in such a way as will please you. Above all, I have laid it upon myself to save the immateriality of the soul, which Locke leaves doubtful. I justify also the existence of innate ideas, and show that the soul produces their perception out of itself. Axioms, too, I approve, while Locke has a low opinion of them. In contradiction to him, I show that the individuality of man, through which he preserves his identity, consists in the duration of the simple or immaterial substance which animates him; that the soul is never without representations; that there is neither a vacuum nor atoms; that matter, or the passive principle, cannot be conscious, excepting as God unites with it a conscious substance. We disagree, indeed, in numerous other points, for I find that he rates too low the noble philosophy of the Platonic school (as Descartes did in part), and substitutes opinions which degrade us, and which may become hurtful to morals, though I am persuaded that Locke’s intention was thoroughly good. I have made these comments in leisure hours, when I have been journeying or visiting, and could not occupy myself with investigations requiring great pains. The work has continued to grow under my hands, for in almost every chapter, and to a greater extent than I had thought possible, I have found matter for remark. You will be astonished when I tell you that I have worked upon this as upon something which requires no great pains. But the fact is, that I long ago established the general principles of philosophic subjects in my mind in a demonstrative way, or pretty nearly so, and that they do not require much new consideration from me.”
Leibniz goes on to add that he has put these reflections in the form of a dialogue that they may be more attractive; has written them in the popular language, rather than in Latin, that they may reach as wide a circle as the work of Locke; and that he hopes to publish them soon, as Locke is already an old man, and he wishes to get them before the public while Locke may still reply.
But unfortunately this last hope was destined to remain unrealized. Before the work of revision was accomplished, Locke died. Leibniz, in a letter written in 1714, alludes to his controversy with Locke as follows: “I do not like the thought of publishing refutations of authors who are dead. These should appear during their life, and be communicated to them.” Then, referring to his earlier comments, he says: “A few remarks escaped me, I hardly know how, and were taken to England. Mr. Locke, having seen them, spoke of them slightingly in a letter to Molineux. I am not astonished at it. We were somewhat too far apart in principle, and that which I suggested seemed paradoxical to him.” Leibniz, according to his conviction here expressed, never published his “Nouveaux Essais sur l’Entendement Humain.” Schaarschmidt remarks that another reason may have restrained him, in that he did not wish to carry on too many controversies at once with the English people. He had two on his hands then,—one with the Newtonians regarding the infinitesimal calculus; the other with Bishop Clarke regarding the nature of God, of time and space, of freedom, and cognate subjects. However, in 1765, almost fifty years after the death of Leibniz, his critique upon Locke finally appeared.
It is somewhat significant that one whose tendency was conciliatory, who was eminently what the Germans delight to call him, a “mediator,” attempting to unite the varied truths which he found scattered in opposed systems, should have had so much of his work called forth by controversy. Aside from the cases just mentioned, his other chief work, the Theodicy, is, in form, a reply to Bayle. Many of his minor pieces are replies to criticism or are developments of his own thought with critical reference to Descartes, Malebranche, and others. But Leibniz has a somewhat different attitude towards his British and towards his Continental opponents. With the latter he was always in sympathy, while they in turn gave whatever he uttered a respectful hearing. Their mutual critiques begin and end in compliments. But the Englishmen found the thought of Leibniz “paradoxical” and forced. It seemed to them wildly speculative, and indeed arbitrary guess-work, without any special reason for its production, and wholly unverifiable in its results. Such has been the fate of much of the best German thought since that time in the land of the descendants of Newton and Locke. But Leibniz, on the other hand, felt as if he were dealing, in philosophical matters at least, with foemen hardly worthy of his steel. Locke, he says, had subtlety and address, and a sort of superficial metaphysics; but he was ignorant of the method of mathematics,—that is to say, from the standpoint of Leibniz, of the method of all science. We have already seen that he thought the examination of a work which had been the result of the continued labor of Locke was a matter for the leisure hours of his courtly visits. Indeed, he would undoubtedly have felt about it what he actually expressed regarding his controversy with Clarke,—that he engaged in it
“Ludus et jocus, quia in philosophia
Omnia percepi atque animo mecum ante peregi.”
He regarded the English as superficial and without grasp of principles, as they thought him over-deep and over-theoretical.
From this knowledge of the external circumstances of the work of Leibniz and its relation to Locke, it is necessary that we turn to its internal content, to the thought of Leibniz as related to the ideas of Locke. The Essay on the Human Understanding is, as the name implies, an account of the nature of knowledge. Locke tells us that it originated in the fact that often, when he had been engaged in discussions with his friends, they found themselves landed in insoluble difficulties. This occurred so frequently that it seemed probable that they had been going at matters from the wrong side, and that before they attempted to come to conclusions about questions they ought to examine the capacity of intelligence, and see whether it is fitted to deal with such questions. Locke, in a word, is another evidence of that truth which lies at the basis of all forms of philosophical thought, however opposed they may be to one another,—the truth that knowledge and reality are so organic to each other that to come to any conclusion about one, we must know something about the other. Reality equals objects known or knowable, and knowledge equals reality dissolved in ideas,—reality which has become translucent through its meaning.
Locke’s Essay is, then, an account of the origin, nature, extent, and limitations of human knowledge. Such is its subject-matter. What is its method? Locke himself tells us that he uses the “plain historical method.” We do not have to resort to the forcing of language to learn that this word “historical” contains the key to his work. Every page of the Essay is testimony to the fact that Locke always proceeds by inquiring into the way and circumstances by which knowledge of the subject under consideration came into existence and into the conditions by which it was developed. Origin means with Locke, not logical dependence, but temporal production; development means temporal succession. In the language of our day, Locke’s Essay is an attempt to settle ontological questions by a psychological method. And as we have before noticed, Leibniz meets him, not by inquiry into the pertinence of the method or into the validity of results so reached,
