[2] As a lawyer, he was the redactor of the codification of Polish criminal and civil law made at the behest of King Casimir the Great.

In 1357, he convened a provincial synod in Kalisz, which passed 16 resolutions on the law and current affairs of the Church, including a decision to apply ecclesiastical punishments such as the interdict to anyone acting against the clergy or their landed estates.

He built castles in Łowicz, Uniejów, Kamień Krajeński and Opatówek, bishop's mansions in Gniezno, Kalisz, Wieluń and Łęczyca, and a brick church in his hometown of Skotniki.

In it, the prince, whose state included Skierniewice, confirmed the archbishop's ownership of the area, and bestowed new privileges on the villagers.

During his reign, Skierniewice and the entire archbishop's estate began to record economic development and quickly grew into a fairly large settlement that could be transformed into a city[citation needed].