We should naturally have expected some such account of Philosophy as that it begins with a limitation of the questions to which men can hope for an answer, and ends in an ordered arrangement of the principles of knowledge, with ultimate reference to the conditions of morals and the structure of civil societies.

We should naturally have expected to find, what indeed we do find, that the characteristic of the philosopher is to "admit nothing without proof, never to acquiesce in illusory notions; to draw rigorously the dividing lines of the certain, the probable, the doubtful; above all things never to pay himself with mere words." But then these wholesome prescriptions come in an article whose definitions and distribution of philosophy are simply a reproduction from Christian Wolff, and the methods and dialect of Wolff are as essentially alien from the positive spirit of the Encyclopaedia as they were from the mystic spirit of Jacobi.
Wolff's place in the philosophical succession of German speculation (1679-1754) is between Leibnitz and Kant, and until Kant came his system was dominant in the country of metaphysics.[184] It is from Wolff that Diderot borrows and throws unassimilated into the pages of the Encyclopaedia propositions so fundamentally incongruous as this, that "among all possibles there must of necessity be a Being subsisting by himself; otherwise there would be possible things, of the possibility of which no account could be given, an assertion that could never be made." It is a curious thing, and it illustrates again the strangely miscellaneous quality of Diderot's compilation, that the very article which begins by this incorporation of the author of a philosophical system expounded in a score of quartos, ends by a vigorous denunciation of the introduction of the systematic spirit into philosophy.
I shall venture to quote a hardy passage from another article (_Pyrrhonienne_) which some will think a measure of Diderot's philosophical incompetency, and others will think a measure of his good sense.

"We will conclude," he says, "for our part that as all in nature is bound together, there is nothing, properly speaking, of which man has perfect, absolute, and complete knowledge, because for that he would need knowledge of all.

Now as all is bound together, it inevitably happens that, from discussion to discussion, he must come to something unknown: then in starting again from this unknown point, we shall be justified in pleading against him the ignorance or the obscurity or the uncertainty of the point preceding, and of that preceding this, and so forth, up to the most evident principle.

So we must admit a sort of sobriety in the use of reason.