Council of Trent: Session XXV, Reformation, Chapter V

CHAPTER V. The conditions and obligations imposed on Benefices shall be observed.

Reason requires, that, in regulations which have been well established, no alteration be made by any ordinances to the contrary. Whenever, therefore, by virtue of the erection or foundation of any benefices, or in consequence of other regulations, certain qualifications are required, or certain obligations are attached thereunto, they shall not be derogated from in the collation, or in any other arrangement whatsoever in regard of the said benefices. The same also shall be observed as to prebends assigned to teachers of theology, masters, doctors, priests, deacons, or subdeacons, whenever such prebends have been established in this manner, in such sort that, in no provision whatever shall anything be altered in regard of the said qualifications and orders ; and any provision made otherwise shall be accounted surreptitious.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).