The interruption of eighty years counts for no more than the twinkling of an eye in the history of the transformation of the basis of thought.

And the interruption has for the present come to a close.

Europe again sees the old enemies face to face; the Church, and a Social Philosophy slowly labouring to build her foundations in positive science.

It cannot be other than interesting to examine the aims, the instruments, and the degree of success of those who a century ago saw most comprehensively how profound and far-reaching a metamorphosis awaited the thought of the Western world.

We shall do this 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.