At Mantua he gained the esteem of Guglielmo Gonzaga.

At Milan he was admitted to familiar intimacy with the sainted Carlo Borromeo, who consulted him upon matters of reform in the diocese, and insisted on his hearing confessions.

This duty was not agreeable to Sarpi; and though he habitually in after life said Mass and preached, he abstained from those functions of the priesthood which would have brought him into close relation with individuals.

The bent of his mind rendered him averse to all forms of superstition and sacerdotal encroachments upon the freedom of the conscience.

As he fought the battle of political independence against ecclesiastical aggression, so he maintained the prerogatives of personal liberty.