His name is known from the 13th century chronicle “Sede Vacante with krakowski” which lists the names of the first nine Bishops but which does not provide years.[3] He arrived in Poland probably from Cologne, where the Archbishop was Hermann, uncle of Casimir the Restorer, or from Leodium.
Prince Casimir the Restorer considered moving the capital of the Polish church to Kraków during his reconstruction of the church. Some researchers speculate, however, that Aron received the Pallium as a personal badge of honour rather than a restructuring of the church.
He was a strong supporter of Duke Casimir the Restorer, and an organizer of the Church in Kraków and a supporter of the Clunic movement. He is also credited with founding the library at Kraków. The chapter of Kraków has adopted for his personal coat of arms.
He died in 1059, either on 15 May or on 9 October. Bishop Aron is a character in the historical novel, Silver Eagles by Teodor Parnicki.