Juan Fernández de Heredia, Great Master of the Saint John of Jerusalem’s Order, passionate person for grecolatin culture and great humanist promoter, find hollow between his occupations as State man for promoting numerous works, and between these, a translation of the Plutarc’s Parallel Lives, which is recovered in this way for Occident. Two translators took order of such commission: one byzantine translator, Talodiqui, and one aragonese translator, Nicolaus; the latter translate what the byzantine translator had translated in byzantine language. The byzantine version has not arrived to us; yes, nevertheless, the byzantine version. This paper analyses several questions which have to see with the difficulty of a translator function not from the Plutarc’s aragonese text, but a intermediate text that have disappeared. Nevertheless, the aragones translation not ceases to see one linguistic invaluable document for the studious of romanist and aragonese language.