He afterwards supplied the deficiencies of his education by private study, and the knowledge which he thus acquired was more substantial and extensive than that of any of his Italian contemporaries, though it was not till late in life that he became acquainted with the Greek and French languages.

His love of independence induced him to refuse several very advantageous offers that were made to him both by the Church and by wealthy collectors of books at Venice, and he continued to live as a simple abbe.

While this work was in course of publication, he also wrote Dissertazione Storica intorno alla Publica Libreria di S. Marco (Venice, 1774), in which he discussed and solved a great many questions connected with the history of literature.

He then prepared a similar work on the history of the library of the academy at Padua, whither he had accompanied his friend Farsetti; but the materials which he collected for that purpose were unfortunately left in the hands of Colle, the historiographer of that institution, through whose carelessness they were lost.

These works alone would have sufficed to secure to Morelli an honorable place among the eminent bibliographers of modern times; but he acquired a still greater reputation as librarian of the library of St. Mark — an office which he received in 1778, and which he held until his death on 5 May 1819.