“The Index: The popular name for the Index Liborum Prohibitorum (Latin, ‘index of prohibited books’), the Vatican’s ever-changing list of proscribed publications, which Roman Catholics were forbidden to read except in special circumstances. The first index was made by the Inquisition in 1557, although St. Gelasius (pope 492-96) issued a list of prohibited writings in 494. In 1571 Pope Pius V set up a Congregation of the Index to supervise the list, and in 1917 its duties were transferred to the Holy Office. In addition to the Index there was the ‘Codex Expurgatorious’ of writings from which offensive doctrinal or moral passages were removed. The Index and the Codex were banned in 1966.
All books likely to be contrary to faith and morals, including translations of the Bible not authorized by the Church, were formerly placed on the Index. Among authors wholly or partly prohibited were: Joseph Addison, Francis Bacon, Geoffrey Chaucer, Benedetto Croce, Gabriele D’Annunzio, Rene Descartes, Edward Gibbon, Oliver Goldsmith, Victor Hugo, John Locke, John Milton, Montaigne, Girolamo Savonarola, Voltaire and, for a long time, Copernicus, Dante and Galen.
Index Liborum Prohibitorum was also the title given to the first ever bibliography in English of erotic and pornographic writing. It was published in 1877 by Henry Spencer Ashbee (1834-1900), businessman, book collector and member of the Royal Academy of Madrid, who left his collections of erotic and Spanish literature to the British Museum. Some experts have suggested Ashbee as the pseudonymous ‘Walter,’ author of the pornographic classic My Secret Life (1888-92).”
Excerpted from: Crofton, Ian, ed. Brewer’s Curious Titles. London: Cassell, 2002.