Diderot had thought them worth compiling into an article. It was not merely in the details of the practical arts that Diderot wrote from material acquired at second-hand. The article on the Zend-Avesta is taken from the Annual Register for 1762. The long series of articles on the history of philosophy is in effect a reproduction of what he found in Bayle, in Deslandes, and in Brucker. There are one or two considerable exceptions. Perhaps the most important is under the heading of Spinosa, to which we shall return presently. The article on _Hobbisme_ contains an analysis, evidently made by the writer's own hand, of the bulk of Hobbes's propositions; it is scarcely, however, illuminated by a word of criticism. If we turn to the article on _Societe_, it is true, we find Hobbes's view of the relations between the civil and temporal powers tolerably effectively combated, but even here Diderot hardly does more than arm himself with the weapons of Locke. Of course, he honestly refers his readers to these sources of wider information.[181] All that we can say of the articles on the history of philosophy is that the series is very complete; that Diderot used his matter with intelligence and the spirit of criticism, and that he often throws in luminous remarks and far-reaching suggestions of his own. This was all that the purpose of his book required. To imitate the laborious literary search of Bayle or of Brucker, and to attempt to compile an independent history of philosophy, would have been to sacrifice the Encyclopaedia as a whole, to the superfluous perfection of a minor part. There is only one imperative condition in such a case, namely, that the writer should pass the accepted material through his own mind before reproducing it. With this condition it was impossible for a man of Diderot's indefatigable energy of spirit, not as a rule to comply.