The word has been derived from the A.S. _ymb-ren_, a circuit or revolution (from _ymb_, around, and _rennen_, to run); or by process of agglutination and phonetic decay, exemplified by the Ger. _quatember_, Dutch _quatertemper_ and Dan. _kvatember_, from the Lat. _quatuor tempora_. The occurrence of the Anglo-Saxon compounds _ymbren-tid_, _ymbren-wucan_, _ymbren-fæstan_, _ymbren-dagas_ for Ember tide, weeks, fasts, days, favours the former derivation, which is also confirmed by the use of the word _imbren_ in the acts of the council of Ænham, A.D. 1009 ("jejunia quatuor tempora quae _imbren_ vocant"). It corresponds also with Pope Leo the Great's definition, "jejunia ecclesiastica per totius anni circulum distributa." The observance of the Ember days is confined to the Western Church, and had its origin as an ecclesiastical ordinance in Rome. They were probably at first merely the fasts preparatory to the three great festivals of Christmas, Easter and Pentecost. A fourth was subsequently added, for the sake of symmetry, to make them correspond with the four seasons, and they became known as the _jejunium vernum_, _aestivum_, _autumnale_ and _hiemale_, so that, to quote Pope Leo's words, "the law of abstinence might apply to every season of the year." An earlier mention of these fasts, as four in number--the first known--is in the writings of Philastrius, bishop of Brescia, in the middle of the 4th century. He also connects them with the great Christian festivals (_De haeres._ 119). In Leo's time, A.D. 440-461, Wednesday, Friday and Saturday were already the days of special observance. From Rome the Ember days gradually spread through the whole of Western Christendom. Uniformity of practice, however, was of somewhat slow growth. Neither in Gaul nor Spain do they seem to have been generally recognized much before the 8th century. Their introduction into Britain appears to have been earlier, dating from Augustine, A.D. 597, acting under the authority of Gregory the Great. The general period of the four fasts being roughly fixed, the precise date appears to have varied considerably, and in some cases to have lost its connexion with the festivals altogether. The _Ordo Romanus_ fixes the spring fast in the first week of March (then the first month); the summer fast in the second week of June; the autumnal fast in the third week of September; and the winter fast in the complete week next before Christmas eve. Other regulations prevailed in different countries, until the inconveniences arising from the want of uniformity led to the rule now observed being laid down under Pope Urban II. as the law of the church, in the councils of Piacenza and Clermont, A.D. 1095.