This, as we have said, is the period of formation, extending from the end of the first century to the end of the sixth. In it we find the first outline of the Breviary, in which can be distinguished little by little the distinction between the canonical hours, the elements of which they are composed, and also a first attempt at an ordo with liturgical week, office de tempore, and calendar of feasts. In tracing out the developments in the churches of the East and West, it is well to distinguish two epochs: I, the Ante-Nicene epoch, from the beginning of the second century to the Council of Nicæa in 325; 2, the Post-Nicene epoch, from the Council of Nicæa to the end of the sixth century (328-590).