l'un a l'autre_ (1776), and two posthumous works, _Logique_
(1781) and the unfinished _Langue des calculs_ (1798). In his earlier
days in Paris he came much into contact with the circle of Diderot. A
friendship with Rousseau, which lasted in some measure to the end, may
have been due in the first instance to the fact that Rousseau had been
domestic tutor in the family of Condillac's uncle, M. de Mably, at
Lyons. Thanks to his natural caution and reserve, Condillac's relations
with unorthodox philosophers did not injure his career; and he justified
abundantly the choice of the French court in sending him to Parma to
educate the orphan duke, then a child of seven years. In 1768, on his
return from Italy, he was elected to the French Academy, but attended no
meeting after his reception. He spent his later years in retirement at
Flux, a small property which he had purchased near Beaugency, and died
there on the 3rd of August 1780.

Though Condillac's genius was not of the highest order, he is important
both as a psychologist and as having established systematically in
France the principles of Locke, whom Voltaire had lately made
fashionable. In setting forth his empirical sensationism, Condillac
shows many of the best qualities of his age and nation, lucidity,
brevity, moderation and an earnest striving after logical method.
Unfortunately it must be said of him as of so many of his
contemporaries, "er hat die Theile in seiner Hand, fehlt leider nur der
geistiger Band"; in the analysis of the human mind on which his fame
chiefly rests, he has missed out the active and spiritual side of human
experience. His first book, the _Essai sur l'origine des connaissances
humaines_, keeps close to his English master. He accepts with some
indecision Locke's deduction of our knowledge from two sources,
sensation and reflection, and uses as his main principle of explanation
the association of ideas. His next book, the _Traite des systemes_, is a
vigorous criticism of those modern systems which are based upon abstract
principles or upon unsound hypotheses. His polemic, which is inspired
throughout with the spirit of Locke, is directed against the innate
ideas of the Cartesians, Malebranche's faculty--psychology, Leibnitz's
monadism and preestablished harmony, and, above all, against the
conception of substance set forth in the first part of the _Ethics_ of
Spinoza. By far the most important of his works is the _Traite des
sensations_, in