The paper deals with two texts by Mařík Rvačka, a participant in the Council of Constance, whose new copies were found in the Vatican Palatine Library and in the Library of St. James Church in the Municipal archive in Brno. The author of these texts, the prior of the Cyriac order and one of the leading critics of the Czech reformation, refers in them to the contemporary bad state of the Church. His words were aimed especially against the expansion of simony. In the second tract, he critically opposes the communion under both kinds by laymen that was widespread in Bohemia in the second decade of the 15th century.