A satire on the intrinsic vanity of the social order and an exhortation towards a humanistic Christianity, Erasmus's Praise of Folly--written in 1509 and put on the Index of forbidden books by the Council of Trent in 1559 after becoming the greatest literary success of the Humanistic Age-- is the towering achievement of one of the most brilliant minds of all time, and one of the most influential books ever written.