Quo graviora, or Quo graviora mala,[1] was an apostolic constitution promulgated by Pope Leo XII on 13 March 1825, in which he decreed the prohibition of membership in Masonic lodges in perpetuity.
Leo quoted Pope Clement XII's papal bull In eminenti (1738), Pope Benedict XIV's bull Providas Romanorum (1751) and Pope Pius VII's bull Ecclesiam a Jesu Christo (1821) in full,[2]: Sections 2-6 and briefly also from Pope Clement XIII's encyclical letter A quo die (1758).[2]: Section 7 Following his quotations in full of the declarations of his predecessors, he states that "immediately" after his election to the papacy, he set about "exposing what the state of clandestine sects was, what their number was, what their power was". In his assessment, the "arrogance" of the secret societies "had grown principally on account of the multitude of them, increased by [birth] the new sects".
In particular, secret societies formed within universities were a particular problem. These he referred to as "Universitaria" because their "seat and domicile in many universities of learning" gave them particular influence over generations of young people.[2]: Section 7
Pope Gregory XVI refers to Leo's constitution in an apostolic letter of his own, Ad Gravissimas (1843).[1]
References
- 1.[1.2]Pope Gregory XVI, Ad Gravissimas, in Italian, published on 31 August 1843, accessed on 12 May 2026
- 2.[2.2][2.3]Pope Leo XII, Quo graviora, Papal Encyclicals Online, published on 13 March 1826, accessed on 27 June 2026