In 1872 he was elected master of conferences at the Ecole Normale, and was made doctor of philosophy in recognition of his two treatises, Platonis Hippias Minor sive Socratica contra liberum arbitrium argumenta and La Liberte et le determinisme.
Some general information as to the Platonic doctrines (chiefly in a Neoplatonic garb) was obtainable from the commentary with which Chalcidius (6th century) accompanied his translation, from the work of Apuleius (2nd century) De dogmate Platonis, and indirectly from the commentary of Macrobius (c. 400) on the Somnium Scipionis of Cicero, and from the writings of St Augustine.
9 De dogmate Platonis, i.
The needless bitterness of his attacks upon Plato (in the Comparatio Aristotelis et Platonis), which drew forth a powerful response from Bessarion (q.v.), and the manifestly hurried and inaccurate character of his translations of Plato, Aristotle and other classical authors, combined to ruin his fame as a scholar, and to endanger his position as a teacher of philosophy.
He became more and more attracted to the study of Plato and Aristotle, and his doctor's dissertation (1826) was an attempt to reach through Aristotle's criticisms a more accurate knowledge of the Platonic philosophy (Platonis de ideis et numeris doctrina ex Aristotele illustrate).