[Illustration: Fig. 186.--Chasuble, Mitre, and Stole of St. Thomas à Becket, Archbishop of Canterbury (1117–1170); preserved in the Cathedral of Sens.--Cloth and Embroidery of the Twelfth Century.] Before choristers were regularly introduced many churches had _psalmists_, who constituted a distinct minor order. These psalmists were succeeded by chanting clerks. In the reign of the Emperor Justinian, the metropolitan church of Constantinople possessed twenty-six choristers and a hundred and ten readers. In the fifteenth canon of the Council of Laodicea we read that “none but the canonical choristers are allowed to sing in the church.” The congregation, however, still kept to the custom of joining their voices to those of the choristers. At first there no doubt existed a special dress worn during the hours of service, but it is supposed that it was only in its colour, which was white, that this dress differed from that worn by the deacons and the priests in everyday life. The maniple (_manipulum_) and the stole (_stola_), accessories to the alb, which was the original vestment worn by the priest, were not adopted and consecrated by the liturgy till the third or fourth centuries. The deacons only wore the stole during the sacrament, but the priests wore it continuously, as a mark of their sacerdotal dignity. The use of the chasuble was subsequent to that of the stole, the alb, and the dalmatic. The chasuble is first mentioned in the twenty-seventh canon of the Fourth Council of Toledo (in 527 A.D.).