Abstract
The state of liturgy and liturgical singing often depended on the care from leading religious personalities. To the liturgical practice in Prague Cathedral significantly contributed Dean Vít, Bishop Tobias of Bechyně and in the 14th century Archbishop Arnestus of Pardubice.
The latter ordered in 1363 for the Prague's Cathedral chapter a set of monumental codices. In the present study, the importance of these books is assessed, as well as the activity of Arnestus as the leader of the Czech church.