Liber gratissimus

work by Peter Damian

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July 16, 2026

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The Liber gratissimus is a significant work by St. Peter Damian, a prominent Roman Catholic cardinal and a key figure in the Gregorian Reform movement of the 11th century. Written around 1052, the book's title translates to "Most-Favored Book".1

The Liber gratissimus primarily addresses the issue of simony, which is the buying or selling of spiritual goods or church offices. Damian strongly condemned the purchase of clerical offices but defended the validity of sacraments administered by those who had committed simony. This work was instrumental in shaping the papacy's stance on simony during a critical period of reform within the church.21

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St. Peter Damian
Early life and career
…particularly evident in Damian’s tract Liber gratissimus (1052; “Most-Favored Book”), which treated the problem of simony (the purchase of ecclesiastical offices) and the validity of the sacraments bestowed by a simoniac cleric. Although he strongly condemned the purchase of office by clergymen, Damian defended the validity of the sacraments they…
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…particularly evident in Damian’s tract Liber gratissimus (1052; “Most-Favored Book”), which treated the problem of simony (the purchase of ecclesiastical offices) and the validity of the sacraments bestowed by a simoniac cleric. Although he strongly condemned the purchase of office by clergymen, Damian defended the validity of the sacraments they…
Read More