In Catholic and Eastern Orthodox tradition, incorruptibility is the belief that divine intervention lets the bodies of some saints and beatified people avoid normal decay through autolysis and putrefaction. The Catholic Church verifies claims under canon law: bishop authorized inspections, sometimes a pontifical commission, a written medical report, and resealing with ribbons and wax. Witnesses often report a sweet odor of sanctity, and embalming or organ removal disqualifies a body. When Pope John XXIII was found intact, officials pointed to his embalming and his sealed triple coffin, where oxygen loss starves aerobic decay bacteria.

Bernadette Soubirous of Lourdes was inspected in 1919 and 1925 and now lies with wax coverings on her face and hands, and John Vianney is shown under a wax mask, partly because preserved tissue darkens and sinks or turns to waxy adipocere. Teresa of Ávila’s remains were judged unchanged in 1750, 1914 and again in 2024, while Bonaventure found only the tongue and jaw of preacher Anthony of Padua intact in 1263. Incorruptibility is no longer a required miracle for sainthood. The Tablet has reported repairs with wax and silicone, and Monsignor Robert Sarno has called the belief false, citing cold, oxygen loss and soil. Louis Ginzberg’s Legends of the Jews records similar claims about the scribe Baruch, whose tomb is in Iraq.

• How canon law turns an exhumation into something close to a forensic investigation
• Saponification and grave wax, and why wax masks are applied for appearance
• Peat bog bodies as evidence that acidic soil can preserve skin like leather
• Alexander of Svir’s relics, seized by the Bolsheviks in 1918, kept at Petrograd’s Military Medical Academy and recovered in 1997
• Joasaph of Belgorod’s body, taken in 1918, found in Leningrad’s Museum of Religion and Atheism and returned in 1991