 Abbot Adalard of Corbie (d. 826) was Emperor Charlemagne's chief adviser, and described the running of the government in his work "De ordine palatii".There he praises the great merits of his imperial staff, made up of household "servii proprii" (serfs) who were the first ministerials authoritatively recorded.His letters specify that not only were they considered exceptional by their superiors, but the ministerials also mentored their successors in a form of administrative apprenticeship program.