CCC 1290

In the first centuries Confirmation generally comprised one single celebration with Baptism, forming with it a "double sacrament," according to the expression of St. Cyprian. Among other reasons, the multiplication of infant baptisms all through the year, the increase of rural parishes, and the growth of dioceses often prevented the bishop from being present at all baptismal celebrations. In the West the desire to reserve the completion of Baptism to the bishop caused the temporal separation of the two sacraments. the East has kept them united, so that Confirmation is conferred by the priest who baptizes. But he can do so only with the "myron" consecrated by a bishop.