The value of this sort of criticism is likely to be small and evanescent. If the system used as a standard is meagre and narrow, if it is without comprehensiveness and flexibility, it does not repay after-examination. The fact that the “Nouveaux Essais” of Leibniz have escaped the oblivion of the philosophical criticism of his day is proof, if proof still be needed, of the reasoned basis, the width of grasp, the fertility of suggestion which characterize the thought of Leibniz. But the fact that the criticism is, after all, external and not internal has made necessary the foregoing extended account of his method and general results.
On the other hand, what of Locke? How about him who is the recipient of the criticism? I assume that no extended account of his ideas is here necessary, and conceive myself to be justified in this assumption by the fact that we are already better acquainted with Locke. This acquaintance, indeed, is not confined to those who have expressly studied Locke. His thought is an inheritance into which every English-speaking person at least is born. Only he who does not think escapes this inheritance. Locke did the work which he had to do so thoroughly that every Englishman who will philosophize must either build upon Locke’s foundations, or, with conscious purpose, clear the ground before building for himself. And it would be difficult to say that the acceptance of Locke’s views would influence one’s thought more than their rejection. This must not, of course, be taken too literally. It may be that one who is a lineal descendant of Locke in the spiritual generations of thought would not state a single important truth as Locke stated it, or that those who seek their method and results elsewhere have not repudiated the thought of Locke as expressly belonging to him.
But the fundamental principles of empiricism: its conception of intelligence as an individual possession; its idea of reality as something over against and distinct from mind; its explanation of knowledge as a process of action and reaction between these separate things; its account of our inability to know things as they really are,—these principles are congenital with our thinking. They are so natural that we either accept them as axiomatic, and accuse those who reject them of metaphysical subtlety, or, staggered perchance by some of their results, give them up with an effort. But it is an effort, and a severe one; and there is none of us who can tell when some 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