most properly in connection with Diderot.

Whether we accept or question Comte's strong description of Diderot as
the greatest genius of the eighteenth century, it is at least undeniable
that he was the one member of the great party of illumination with a
real title to the name of thinker. Voltaire and Rousseau were the heads
of two important schools, and each of them set deep and unmistakable
marks both on the opinion and the events of the century. It would not be
difficult to show that their influence was wider than that of the
philosopher who discerned the inadequateness of both. But Rousseau was
moved by passion and sentiment; Voltaire was only the master of a
brilliant and penetrating rationalism. Diderot alone of this famous trio
had in his mind the idea of scientific method; alone showed any feeling
for a doctrine, and for large organic and constructive conceptions. He
had the rare faculty of true philosophic meditation. Though immeasurably
inferior both to Voltaire and Rousseau in gifts of literary expression,
he was as far their superior in breadth and reality of artistic
principle. He was the originator of a natural, realistic, and
sympathetic school of literary criticism. He aspired to impose new forms
upon the drama. Both in imaginative creation and in criticism, his work
was a constant appeal from the artificial conventions of the classic
schools to the actualities of common life. The same spirit united with
the tendency of his philosophy to place him among the very few men who
have been great and genuine observers of human nature and human
existence. So singular and widely active a genius may well interest us,
even apart from the important place that he holds in the history of
literature and opinion.