His residence at Florence and Rome brought him into contact with brilliant men of his order, e.g. Giuseppe Agostino Orsi, Divelli and Daniello Concina, and greatly facilitated his progress in his studies.

Owing to his office he had to take part in the controversy between the Appellants (Jansenists) and the Jesuits, and displayed an impartiality which greatly increased the difficulties of his anxious and laborious position.

In a published writing on this question, he dealt severely with the Jesuit party who opposed the beatification; but he was not less energetic in dealing with their opponents, the Appellants and Jansenist Church of Utrecht.

Mamachi's great work was to have been his "Christian Antiquities", but his labours in the field of dogma and jurisprudence absorbed so much of his time that he published only four of the twenty books that he planned.

Moreover, he lived in an age when the good method inaugurated by Antonio Bosio had been abandoned and, considered as an archaeological work, the synthesis which he had projected is valueless.