The Reformatio Sigismundi document appeared in connection with efforts to reform the Holy Roman Empire during the reign of Emperor Sigismund (1410–1437).
It was produced in 1439 at the Council of Basle, published by an anonymous author, and referred to the injustice of the German rulers.
The Reformatio stands at the beginning of a trend to no longer publish constitutional and political principles solely in Latin, but also in German.
The text contained a teaching of the sacraments and argued in favour of the marriage of priests and the secularization of church property.
In addition it included a vision of Emperor Sigismund's about the appearance of a priest-king Frederick and plans for a wide reform of the monarchy (and emperorship) and the (German) empire.