In Praise of Folly, also translated as The Praise of Folly (Latin: Stultitiae Laus or Moriae Encomium), is an oration written in Latin in 1509 by Desiderius Erasmus of Rotterdam and first printed in June 1511. Inspired by previous works of the Italian humanist Faustino Perisauli's De Triumpho Stultitiae, it is a spiralling satirical attack on all aspects of human life, not ignoring superstitions and religious corruption, but with a pivot into an orthodox religious purpose.
Erasmus revised and extended his work, which, he claims, was originally written in the span of a week while sojourning with Sir Thomas More at More's house in Bucklersbury in the City of London. The title Moriae Encomium had a punning second meaning as In Praise of More (in Greek moría translates into "folly"). In Praise of Folly is considered one of the most notable works of the Renaissance and played an important role in the beginnings of the Protestant Reformation.