Hitherto the chasuble had been worn indifferently by all ministers at the eucharist, even by the acolytes; it had been worn also at processions and other non-liturgical functions; it was now exalted into the mass vestment par excellence, worn by the celebrant only, or by his immediate assistants (deacon and subdeacon) only on very special occasions.
The object of the change was primarily to leave the hands of the celebrant freer for the careful performance of the manual acts, and to this end a process of cutting away at the sides of the vestment began, which continued until the tent-shaped chasuble of the 12th century had developed in the 16th into the scapular-like vestment at present in use.
The celebrant himself either sprinkles the ash on his own head in silence, or receives it from the priest of highest dignity present.
But in the middle ages the altars were placed against the east wall of the churches, or else against a reredos erected at the east side of the altar, so as to prevent all access to the table from that side; the celebrant was thus brought round to the west side and caused to stand between the people and the altar.
In that case the celebrant stood behind the altar at mass, and looked over it eastwards towards the people.
It is worn at low masses by the priest only when he goes to and from the altar, at high masses also when the celebrant sits during the singing of the Kyrie, Gloria and Creed, and at processions when these take place outside the church and are not sacramental, and so on.
The chair of the bishop or celebrant was on their east side, and the assistant clergy were ranged on each side of him.
On Easter Sunday the queen ventured to display her personal preference for the Protestant conception of the eucharist by forbidding the celebrant in her chapel to elevate the host.