The passage sounds unpleasantly like an appeal to the crowd in a matter of science, which is as the sin against the Holy Ghost in these high concerns.  What Diderot meant, probably, was to charge Spinosa with inventing a conception of substance which has no relation to objective experience; and further with giving fantastic answers to questions that were in themselves never worth asking, because the answers must always involve a violent wrench of the terms of experience into the sphere transcending experience, and because, moreover, they can never be verified.  Whether he meant this or something else, and whether he would have been right or wrong in such an intention, we may admit that it would have been more satisfactory if in dealing with such a master-type of the metaphysical method as Spinosa, so acute a positive critic as Diderot had taken more pains to give to his objections the utmost breadth of which they were capable.[186]

The article on Leibnitz has less original matter in it than that on Spinosa.  The various speculations of that great and energetic intellect in metaphysic, logic, natural theology, natural law, are merely drawn out in a long table of succinct propositions, while the account of the life and character of Leibnitz is simply taken from the excellent eloge which had been published upon him by Fontenelle in 1716.  Fontenelle’s narrative is reproduced in a generous spirit of admiration and respect for a genius that was like Diderot’s own in encyclopaedic variety of interest, while it was so far superior to Diderot’s in concentration, in subtlety, in precision, in power of construction.  If there could exist over our heads, says Diderot, a species of beings who could observe our works as we watch those of creatures at our feet, with what surprise would such beings have seen those four marvellous insects, Bayle, Descartes, Leibnitz, and Newton.  And he then draws up a little calendar of the famous men, out of whom we must choose the name to be placed at the very head of the human race.  The list contains, besides Julian the Apostate—­who was inserted, we may presume, merely by way of playful insult to the ecclesiastical enemy—­Socrates, Marcus Aurelius, Trajan, Bacon, and the four great names that have just been cited.  Germany derives as much honour from Leibnitz alone, he concludes with unconsidered enthusiasm, as Greece from Plato, Aristotle, and Archimedes, all put together.  As we have said, however, there is no criticism, nor any other sign that Diderot had done more than survey the facade of the great Leibnitzian structure admiringly from without.