Immediately upon Mgr. Mai's appointment to the Secretaryship of the Propaganda, May 15th, 1833, Mezzofanti was installed as Primo Custode, First Keeper of the Vatican Library ; and about the same time he was appointed to a Canonry in St. Peter's. In the midst of the warm congratulations which he received from all sides, it was not without considerable distrust of his own powers, that he entered upon the office of Librarian, as the successor of a scholar so eminent as Angelo Mai.

"It is no ordinary distinction," he wrote to his friend Car. Pezzana, " to be called to succeed Mgr Mai in the care of the Vatican Library,—a post which has derived new brilliancy from the brilliant qualities of its latest occupant: nor can I overcome my apprehension lest the honour which I may gain by my first few hours of office may decline, when it comes to be seen how great is the difference between this distinguished man and his successor. This fear, I confess, is a drawback upon my joy at this happy event; but at the same time, I trust it will also stimulate me to make every effort that the lustre of a position in itself so honourable, may not be tarnished in my person. I have only to wish that your congratulation, coming as it does from a kindly feeling, may be an earnest of the successful exercise of the diligence I am determined to use in my new career, which is all the more grateful and honourable to me, as it furnishes more frequent occasions of corresponding with you."

There is another of his letters of the same period, which to many perhaps will appear trivial, but which points in a still more amiable light, not alone his unaffected piety and humility, but the homely simplicity of his disposition, and the affection with which he cherished all the domestie relations. It is addressed to his cousin, Antonia, who has already been mentioned in a former part of this Memoir, but who, for some years before Mezzofanti's leaving Bologna, had been afflicted with blindness. On the occasion of his appointment, this lady employed the pen of a common friend, Signora Galli, of Bologna, to convey her congratulations to Mezzofanti. It would seem, moreover, that she had intended on the same occasion to make him a present, which Mezzofanti, out of consideration for her limited means, had thought it expedient to' decline.

"Bologna, December 14, 1833. My most esteemed cousin,
Accept, in return for all your kind congratulations and good wishes, my most sincere prayer that God may bestow upon you all the choicest blessings of the approaching festival. There is one present which it is in your power to make me, and one which is especially suitable to a person so entirely devoted to God as you are : it is to offer up the holy communion for me on one of the coming festivals. I, upon my part, will offer the Holy Sacrifice for you on the feast of St. John ; and on the same day I will make a special memento of your good parish priest, the abate Landrino, who once, upon the same day, showed me a kindness which I shall never forget. Pray remember me to him, and also to dear Signora Galli, in whom, as your secretary, you have found an admirable exponent of your affectionate sentiments, for which I am deeply grateful to you both. My nephews unite in best wishes for your health and happiness. Make the best report from me at home, and believe me always, your most affectionate cousin,
JOSEPH MEZZOFANTI."