Institutiones may refer to several works: Institutes of Gaius, legal textbook, written about 161 AD Institutes of Justinian, or "Justinian's Institutes", sixth century, largely based upon the Institutes of Gaius Institutiones Divinarum et Saecularium Litterarum, an encyclopedic work by Cassiodorus, sixth century Institutio canonicorum Aquisgranensis, Institutiones Aquisgranenses, the Instruction of canons of Aachen, disseminated in 816 Institutiones calculi differentialis, Leonhard Euler, published 1755 See also Institute (disambiguation) The Institutes (disambiguation)