Music is a privelged tool for retracing the meanders of cultural evolution. Its study shows how certain customs sometimes lasted for centuries; and how man, ever more mobile, promoted the exchange of specific know-how. 

With greater mobility emerged new practises of varying duration. Some existed for decades, others for several centuries and yet others disappeared for a time to re-emerge once the conditions for their development proved more favourable.

At the threshold of the XXIst century the temptation is great to delve into the past. The means of modern communication, the possibility for  international partners to mobilise themselves around the same project, to share knowledge and solve common problems, prompts us to relive, like so many contemporary events, the arts of the past. Thus history becomes a way of experiencing the challenges of the present, for the structuring of the memory, if it is linked to concerted actions of dissemination and instruction, becomes a ferment of life; it broadens the fields of perception and stimulataes the creative process. The muslim world has safeguarded a large number of song practices directly linked to those of the early Christian communities, such as the chanting of sacred texts, and the practise of collective singing characterised by  certain sufi fraternities. As for the Byzantive world, its musical history is is particularly tied in with that of the latin world. In the different specimens of plainchant that have been preserved in their written form in western Europe (Old Roman, Gregorian, Milanese, Beneventin, Mozarab and Galician chant) one finds many elements related to their origin, their creation and their vocal aesthetic that must be studied in the light of the repertoires of the Orient in which we find a common root, or similar design or aesthetic.