Simony /ˈsaɪməni, ˈsɪ-/ is the act of selling church offices and roles. The practice is named after Simon Magus, who is described in the Acts of the Apostles 8:9–24 as having offered two disciples of Jesus, Peter and John, payment in exchange for their empowering him to impart the power of the Holy Spirit to anyone on whom he would place his hands. The term also extends to other forms of trafficking for money in "spiritual things". Simony was also one of the important issues during the Investiture Controversy.
Although an offense against canon law, Simony became widespread in the Catholic Church in the 9th and 10th centuries. In the canon law, the word bears a more extended meaning than in English law. Simony according to the canonists, says John Ayliffe in his Parergon,
"...is defined to be a deliberate act or a premeditated will and desire of selling such things as are spiritual, or of anything annexed unto spirituals, by giving something of a temporal nature for the purchase thereof; or in other terms it is defined to be a commutation of a thing spiritual or annexed unto spirituals by giving something that is temporal."
In the Corpus Juris Canonici the Decretum and the Decretals deal with the subject. The offender whether simoniacus (one who had bought his orders) or simoniace promotus (one who had bought his promotion), was liable to deprivation of his benefice and deposition from orders if a secular priest, or to confinement in a stricter monastery if a regular. No distinction seems to have been drawn between the sale of an immediate and of a reversionary interest. The innocent simoniace promotus was, apart from dispensation, liable to the same penalties as though he were guilty.