Mill, John Stuart, _Treatise on Liberty_, prohibited in 1851; _Principles of Political Economy_, printed in 1848, prohibited in 1850. Darwin, Erasmus, _Zoönomy_, printed in 1794, prohibited in 1817. (_The Origin of Species_ and the other treatises by Charles Darwin, the grandson of Erasmus, have, curiously enough, escaped the attention of the Index authorities.) Draper, J. W., _History of the Conflict between Religion and Science_, printed (in New York) in 1874, prohibited (in a Spanish version) in 1876. Condorcet, the Marquis, _Esquisse d’un Tableau historique du Progrès de l’Esprit humain_, printed in 1804 as a division in a series of works comprising in all twenty-one volumes, prohibited 1827. Condillac, Abbé de, _Cours d’Étude_, printed (in Paris) in 1773, prohibited in 1836. Ahrens, Henri, _Cours du Droit Naturel_, printed in 1838, prohibited 1868. Cousin, _Cours d’Histoire de la Philosophie_, printed in 1827, prohibited in 1844. This is the only one of the long series of works by this author that finds place in the Index. Cousin was induced by his friends Sibour and Maret, for the purpose of preventing the threatened condemnation of his works by the Congregation of the Index, to write a letter to the Pope. He writes, under date of April 30, 1836, in substance as follows: “As Your Holiness has already been informed, I am myself a devout upholder of the Christian faith and I place all my hopes for the future of mankind upon the maintenance and extension of Christianity. I can but be troubled that my views have been placed in a false light and I have attempted to produce a philosophical treatise which should be entirely free from the possibility of reproach and in the preparation of which I have secured the counsel of scholarly divines. If it may be the case that, notwithstanding my own watchful care and the aid of these scholarly advisers, certain passages which could cause concern to Your Holiness have escaped attention, I will ask that these may be indicated to me. I am more than anxious to correct or to eliminate any expressions or statements that may be open to criticism from the point of view of the Church. My sole purpose is to do all that may be practicable to perfect the text of these modest writings of mine.” Comte, Auguste (†1857), _Cours de Philosophie Positive_, printed in Paris in 1864 with an introduction by Littré, prohibited in the same year. No one of the other works by Comte finds place in the Index. Littré had sharp controversies with Dupanloup in 1863, and was characterised by the Archbishop as an atheist, but no one of Littré’s writings was formally condemned. Taine, Hippolyte Adolphe, _Histoire de la Littérature Anglaise_, printed (in Paris) in 1863, prohibited in 1866. This work had, in 1864, been condemned by the French Academy as tending to undermine the belief in the freedom of the will, the sense of personal responsibility, and morality in general.