Abstract
The basic idea of the present work is this one: supposing the it is not naive nor anachronistic to read the situation psychologically, Ambrose never was a ‘mentor’ who used his friendship to dominate totally Gratian who would have been a weak character. The investigation considers almost the whole reign, in two parts: De fide ad Gratianum libri V. The Council of Aquileia. It aims to develop a more subtle understanding of: the image of each of the two protagonists, as they mirror one another; the history of their links, shaped of course by the existence of powerful cliques at court and by the strict rules governing the relations between a bishop and an emperor; the notion, more broadly, of the progressive establishing of the Christian Empire. This, then, is a work of synthesis. Such an undertaking is timely, given the number, size and importance, of the studies on the subject.