In 1856 he began to teach, and was admitted to the École Normale Supérieure in 1862. In 1885 he gave a course of lectures on Experimental Psychology at the Sorbonne, and in 1888 was appointed professor of that subject at the College of France. His thesis for his doctors' degree, republished in 1882, Hérédité: étude psychologique (5th ed., 1889), was his most important and best known book.
Following the experimental and synthetic methods, he brought together a large number of instances of inherited peculiarities. He paid particular attention to the physical element of mental life, ignoring all spiritual or nonmaterial factors in man. In his work on La Psychologie anglaise contemporaine: l'école expérimentale (1870), he showed his sympathy with the sensationalist school, and again in his translation of Herbert Spencer's Principles of Psychology.
Besides numerous articles, he wrote on Arthur Schopenhauer, Philosophie de Schopenhauer (1874; 7th ed., 1896), and on the contemporary psychology of Germany (La Psychologie allemande contemporaine, 1879; 13th ed., 1898), also four little monographs on Les Maladies de la mémoire (1881; x3th ed., 1898); De la volonté (1883; 14th ed., 1899); De la personnalité (1885; 8th ed., 1899); and La Psychologie de l'attention (1888), which supplied useful data to the study of mental illness.