U radu se obrađuje kratki rukopis (od tridesetak stranica) Frane Petrića koji se nalazi u Biblioteca Ambrosiana u Milanu pod naslovom De numerorum mysteriis (O tajnama brojeva). U rukopisu Petrić iznosi mišljenja pitagorejskih i platoničkih autora o brojevima. Pri tome Petrić preuzima najveći dio njihova učenja, a u nekoliko slučajeva izražava svoje neslaganje s njima i iznosi vlastito mišljenje o nekim pitanjima.The paper deals with the short manuscript (about 30 pages) of Frane Petrić (Franciscus Patricius) which is situated in Biblioteca Ambrosiana in Milan entitled De numerorum mysteriis (On mysteries of numbers). Opinions of Pythagorean and Platonic authors on numbers are presented in the manuscript. Petrić takes over the most part of their learning and in some cases expresses his disagreement with them and brings to light his own opinion on some questions
