A French philosopher, born at Grenoble, of good birth; commenced as a disciple of Locke, but went further, for whereas Locke was content to deduce empirical knowledge from sensation and reflection, he deduced reflection from sensation, and laid the foundation of a sensationalism which, in the hands of his successors, went further still, and swamped the internal in the external, and which is now approaching the stage of self-cancelling zero; he lived as a recluse, and had Rousseau and Diderot for intimate friends (1715-1780).