This page opens the section dedicated to the princes of the fifteenth-century Friuli who are to be mainly identified in the titular bishops of the prestigious and venerable Patriarchate of Aquileia. For ecclesiastical and political reasons these were contemporarily princes and patriarchs, as well as persons of high rank and profile: that is to say personalities able to rule, or at least to represent, their diocese before the pope in a moment of a delicate passage, while the Latin Church, after its difficult coming out of a schism, was entering the Modern Age. Learned men abreast of strong historical and cultural changes, particularly of that scholar renewal Humanism was imposing in Italy, first, and then in Europe, and among the ecclesiastical ranks, as well. According to a specific character of the humanistic age the patriarchs of the first Venetian age in Friuli mainly found their cultural expression in book patronage and collection, which discloses the interests of each of them and the taste trends that were integral part of that refined culture. Almost all these prelates were cardinals and their extant volumes – whose survival is often minimal with respect to much more abundant libraries – get into the category of the libri della porpora (‘the books of the purple dignity’), as stated by Armando Petrucci some years ago to indicate a well defined high-level book typology, between professional need and cultural patronage, that had wide spread among the members of the college of cardinals, or bishops and curia prelates. Pancera, Trevisan, Barbo, Donà e Grimani were all of Venetan origin and very strict pontifical nomination: therefore they were all fixedly tied to the authority and authoritativeness of the Roman pope in years that were on the schism edge. Their patriarchies cover a wide chronological course, since the end of the Gothic Age and the Great Schism to the mature Renaissance period and the Lutheran split. And such a course of time is concentrated in only five personalities who nearly all had in common decisive aspects for themselves and for the history of the Church of Aquileia. With the exception of Donà, who ruled the patriarchate for a very short period, all of them were patriarchs and cardinals.