One of the cardinals acts as president, or prefect, as he is called; the congregation is assisted by a secretary and a certain number of inferior officials, for secretarial and office work.
After the reign of Marcus Aurelius (according to Mommsen) the equites were divided into: (a) viri eminentissimi, the prefects of the praetorian guard; (b) viri perfectissimi, the other prefects and the heads of the financial and secretarial departments; (c) viri egregii, first mentioned in the reign of Antoninus Pius, a title by right of the procurators generally.
It seems probable that he lived in the French embassy in some secretarial or tutorial position.
The secretarial class consisted of six categories: the nishanjis, the defterdars, the reis, the defter emini, the shakk-i-sani (or second class) defterdars and the shakk-i-salis (or third class) defterdars.
In any case Prosper was soon in Rome, attached to the pope in some secretarial or notarial capacity.