CHASUBLE. - A long strip of silk or linen that rests on the shoulders with its two ends hanging down over the chest and that serves to cover the hands while holding sacred objects.
A distinction is made between: 1) the humeral veil of the subdeacon, of silk of the color prescribed for Holy Mass, as a rule without ornament, a) for carrying the prepared chalice to the altar for the Offertory, b) for holding the paten from the Offertory until the "Pater noster"; 2) that of the acolyte who carries the mitre or the pastoral staff in pontifical functions (of linen or of silk without ornament, white or of the color prescribed for the pontifical function); 3) that of the priest in eucharistic benediction, in eucharistic processions and also in carrying the Eucharist or the viaticum to the sick (of silk, always white and richly ornamented).
At first the acolyte "paternarius" held the paten with the "sindon" from the Offertory until the "Pater noster" (Ordo roman., I [Andrieu], 91). This "sindon" was a cloth of fine linen so as not to touch the paten directly with the hand, perhaps in the shape of the present humeral veil ("sub humero habens sindonem in collo ligatam"). The office of the acolyte "paternarius" (it survives in France and in England until the 18th century) was replaced in the 12th-13th century by the subdeacon, who held the paten first with the same "mappula" which, called "offertorium" (Ord. Rom.

[Andrieu], I, 84; V, 55; VI, 50), covered the oblations after their preparation. From the 13th-14th century (Ord. Rom., [Mabillon], XVI, 53, of the year 1311) the manner of wearing the veil changed: the end, which was not used for holding the paten, hung down the back from the right shoulder ("cuius extremitas defluere debet post dextrum humerum"). The present form of the humeral veil came into use in Rome no earlier than the 15th century (Ordo Rom., XV [Mabillon]). The veil of the mitre acolyte, called "tobalea", still absent in the time of Durandus (d. 1296), is already mentioned by the Ordo of Giulio Cajetano (XIV, 53 [Mabillon]) of 1311.
The veil of eucharistic benediction came into use in the 14th century (Ord. Rom., XIV [Mabillon], 77); it was of silk and was worn at first like the subdiaconal veil (the end hung over the left shoulder "sibi pendet super humerum sinistrum"), then like the humeral veil.
Bibliography
Pietro Siffrin