Mezzofanti soon becomes the priest who confesses foreigners in their own language. He asks them to recite common prayers and religious words in their own language. He learns the Sardinian dialect from a maid only by speaking to her one hour every evening. 

Even his regular priestly duties as a confessor now contributed, as his extraordinary duties in the hospitals had done before, to enlarge his stock of languages. He was soon marked out as the " foreigners' confessor" (confessario del forestieri) of Bologna, an office which, in Rome and other Catholic cities, is generally entrusted to a staff consisting of many individuals. Almost every foreigner was sure to find a ready resource in Mezzofanti ; though it more than once happened that, as a preliminary step towards receiving the confession of the party applying for this office of his ministry, he had to place himself as a pupil in the hands of the intending penitent, and to acquire from him or her the rudiments of the language in which they were to communicate with each other.

The process to him was simple enough. If the stranger was able to repeat for him the Commandments, the Lord's Prayer, the Apostles' Creed, or any one of those familiar prayers which are the common property of all Christian countries, or even to supply the names of a few of the leading ideas of Christian theology, as God, sin, virtue, earth, heaven, hell, etc..., it was sufficient for Mezzofanti. 

In many cases he proceeded to build, upon a foundation not a whit more substantial than this, the whole fabric of the grammar, and to a great extent even of the vocabulary, of a language. A remarkable instance of this faculty I shall have to relate in the later years of his life. Another, which belongs to the present period, has been communicated to me by Cardinal Wiseman:

Mezzofanti told me,  that a lady from the island of Sardinia once came to Bologna, bringing with her a maid who could speak nothing but the Sardinian dialect, a soft patois composed of Latin, Italian, and Spanish (e.g., Mezzofanti told me that columba mia is Sardinian for " my wife.")

As Easter approached the girl became anxious and unhappy about confession, despairing of finding a confessor to whom she should be able to make herself understood. The lady sent for Mezzofanti ; but at that time he had never thought of learning the language. He told the lady, nevertheless, that, in a fortnight, he would be prepared to hear her maid's confession. She laughed at the idea; but Mezzofanti persisted, and came to the house every evening for about an hour. When Easter arrived, he was able to speak Sardinian fluently, and heard the girl's confession !