Rational

RATIONAL: A term used ecclesiastically in three meanings. (1) It is applied to the breastplate worn by the Hebrew high priest according to Ex. xxviii. 15 (see High Priest, 1; and Ephod). (2) It is the name given to an episcopal ecclesiastical vestment worn when celebrating mass. The first traces of its employment are not earlier than the tenth century. In form it was either a small breast-shield, or an ornamented narrow band which was worn over the chasuble (see Vestments and Insignia, Ecclesiastical), passing from one shoulder across the back over to the other shoulder and both ends hanging down in front. In the latter case it was the episcopal equivalent of the archiepiscopal pallium, though apparently the employment was restricted to certain bishops (as those of Bamberg, Eichstätt, Lüttich, Minden, and others). In the thirteenth century it seems to have become obsolete in France. (3) The word is used to express an exposition of the significance of divine service, as in the famous work of Durandus (q.v.).