Contrapasso refers to the punishment of souls in Dante

DANTE

Delivery of Advanced Network Technology to Europe is a not-for-profit organisation that plans, builds and operates the international networks that interconnect the various national research and education networks in Europe and surrounding regions...

's Inferno

Inferno (Dante)

Inferno is the first part of Dante Alighieri's 14th-century epic poem Divine Comedy. It is followed by Purgatorio and Paradiso. It is an allegory telling of the journey of Dante through what is largely the medieval concept of Hell, guided by the Roman poet Virgil. In the poem, Hell is depicted as...

, "by a process either resembling or contrasting with the sin itself." A similar process, though a penitential one, occurs in the Purgatorio

Purgatorio

Purgatorio is the second part of Dante's Divine Comedy, following the Inferno, and preceding the Paradiso. The poem was written in the early 14th century. It is an allegory telling of the climb of Dante up the Mount of Purgatory, guided by the Roman poet Virgil...

.

One of many examples of contrapasso occurs in the 4th Bolgia (Inferno, Canto XX), where the sorcerers, astrologers

Astrology

Astrology consists of a number of belief systems which hold that there is a relationship between astronomical phenomena and events in the human world...

, and false prophet

False prophet

In religion, a false prophet is one who falsely claims the gift of prophecy, or who uses that gift for evil ends. Often, someone who is considered a "true prophet" by some people is simultaneously considered a "false prophet" by others....

s have their heads twisted around on their bodies backward, so that they "found it necessary to walk backward, / because they could not see ahead of them." While referring primarily to attempts to see into the future by forbidden means, this also symbolises the twisted nature of magic in general. Such a contrapasso "functions not merely as a form of divine revenge, but rather as the fulfilment of a destiny freely chosen by each soul during his or her life."

The word contrapasso can be found in Canto XXVIII of the Inferno, in which the decapitated Bertran de Born declares:
"Così s'osserva in me lo contrapasso" (XXVIII, 142) which Longfellow translates: "Thus is observed in me the counterpoise" De Born is in the 9th Bolgia of schismatics, for (Dante believes) causing the rebellion of Henry the Young King

Henry the Young King

Henry, known as the Young King was the second of five sons of King Henry II of England and Eleanor of Aquitaine but the first to survive infancy. He was officially King of England; Duke of Normandy, Count of Anjou and Maine.-Early life:Little is known of the young prince Henry before the events...

 against his father, Henry II of England

Henry II of England

Henry II ruled as King of England , Count of Anjou, Count of Maine, Duke of Normandy, Duke of Aquitaine, Duke of Gascony, Count of Nantes, Lord of Ireland and, at various times, controlled parts of Wales, Scotland and western France. Henry, the great-grandson of William the Conqueror, was the...

. He is decapitated there as a contrapasso for his (supposed) act of political decapitation in undermining a rightful head of state.

Dante inherited the idea and the name of contrapasso from theological (Thomas Aquinas

Thomas Aquinas

Thomas Aquinas, O.P. , also Thomas of Aquin or Aquino, was an Italian Dominican priest of the Catholic Church, and an immensely influential philosopher and theologian in the tradition of scholasticism, known as Doctor Angelicus, Doctor Communis, or Doctor Universalis...

's Summa Theologica

Summa Theologica

The Summa Theologiæ is the best-known work of Thomas Aquinas , and although unfinished, "one of the classics of the history of philosophy and one of the most influential works of Western literature." It is intended as a manual for beginners in theology and a compendium of all of the main...

) and literary (Medieval "visions", such as Visio Pauli, Visio Alberici, and Visio Tungdali) sources.