In the liturgical calendar of the Western Christian churches, Ember days are four separate sets of three days within the same week — specifically, the Wednesday, Friday, and Saturday — roughly equidistant in the circuit of the year, that were formerly set aside for fasting and prayer. These days set apart for special prayer and fasting were considered especially suitable for the ordination of clergy. The Ember Days are known in Latin as the quattuor anni tempora (the "four seasons of the year"), or formerly as the jejunia quattuor temporum ("fasts of the four seasons").
Ember Weeks 
The Ember Weeks—the weeks in which the Ember Days occur—are the weeks:
- between the third and fourth Sundays of Advent (although the Common Worship lectionary of the Church of England places them in the week following the second Sunday in Advent);
- between the first and second Sundays of Lent;
- between Pentecost and Trinity Sunday; and
- the week beginning on the Sunday after Holy Cross Day (September 14), the liturgical Third Week of September.
The origins of the observance are open to considerable debate. Some hold that the concept of the observance predates the Christian era, and that since Ember days have never been observed in the Eastern Churches, any pagan origins must lie in the west. Some point to specific Celtic origins, linked to the Celtic custom of observing various festivals at three-month intervals: Imbolc, Beltane, Lughnasadh and Samhain. In any event, the ancient Christian church often sought to co-opt pagan feasts and reorient them to different purposes, and that seems to have been applicable in this instance.
In pagan Rome offerings were made to various gods and goddesses of agriculture in the hope that the deities would provide a bountiful harvest (the feriae messis in July), a rich vintage (the feriae vindimiales in September), or a productive seeding (the feriae sementivae in December). At first the Church in Rome had fasts in June, September, and December. The Liber Pontificalis ascribes to Pope Callixtus I (217-222) a law regulating the fast, although Leo the Great (440-461) considers it an Apostolic institution. When the fourth season was added cannot be ascertained, but Pope Gelasius I (492-496) speaks of all four.
The earliest mention of four seasonal fasts is known from the writings of Philastrius, bishop of Brescia (died ca 387) (De haeres. 119). He also connects them with the great Christian festivals.
The Christian observation of this seasonal observance of the Ember days had its origin as an ecclesiastical ordinance in Rome and spread from there to the rest of the Western Church. They were known as the jejunium vernum, aestivum, autumnale and hiemale, so that to quote Pope Leo's words (A.D. 440 - 461) the law of abstinence might apply to every season of the year. In Leo's time, Wednesday, Friday and Saturday were already days of special observance. In order to tie them to the fasts preparatory to the three great festivals of Christmas, Easter and Pentecost, a fourth needed to be added "for the sake of symmetry" as the Encyclopædia Britannica 1911 has it.
From Rome the Ember days gradually spread unevenly through the whole of Western Christendom. In Gaul they do not seem to have been generally recognized much before the 8th century.
Their observation in Britain, however, was embraced earlier than in Gaul or Spain, interestingly, and Christian sources connect the Ember Days observations with Augustine of Canterbury, AD. 597, said to be acting under the direct authority of Pope Gregory the Great. The precise dates appears to have varied considerably however, and in some cases, quite significantly, the Ember Weeks lost their connection with the Christian festivals altogether. Spain adopted them with the Roman rite in the eleventh century. Charles Borromeo introduced them into Milan in the sixteenth century.
The Ordo Romanus fixed the spring fast in the first week of March (then the first month), thus loosely associated with the first Sunday in Lent; the summer fast in the second week of June, after Whitsunday; the autumnal fast in the third week of September following the Exaltation of the Cross, September 14; and the winter fast in the complete week next before Christmas Eve, following St. Lucy's Day (Dec. 13).
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, at the Council of Piacenza and the Council of Clermont, 1095.
These dates are given in the following mnemonic:
- Dant Crux, Lucia, Cineres, Charismata Dia
- Ut sit in angariâ quarta sequens feria
Or in an old English rhyme
- "Fasting days and Emberings be
- Lent, Whitsun, Holyrood, and Lucie."
The ember days began on the Wednesday immediately following those days. This meant, for instance, that if September 14 were a Tuesday, the ember days would occur on September 15, 17, and 18. As a result the ember days in September could fall after either the second or third Sunday in September. This, however, was always the liturgical Third Week of September, since the First Sunday of September was the Sunday closest to September 1 (August 29 to September 4). As a simplification of the liturgical calendar, Pope John XXIII modified this so that the Third Sunday was the third Sunday actually within the calendar month. Thus if September 14 were a Sunday, September 24, 26 and 27 would be ember days, the latest dates possible; with September 14 as a Saturday, however, the ember days would occur on September 18, 20 and 21 - the earliest possible dates.
Prior to the reforms instituted after the Second Vatican Council, the Roman Catholic Church mandated fasting (only one full meal per day plus two partial, meatless meals) on all Ember Days (which meant both fasting and abstinence from meat on Ember Fridays), and the faithful were encouraged (though not required) to receive the sacrament of penance whenever possible. On February 17, 1966, Pope Paul VI's decree Paenitemini excluded the Ember Days as days of fast and abstinence for Roman Catholics.
The revision of the liturgical calendar in 1969 laid down the following rules for Ember Days and Rogation days:
- In order to adapt the rogation and ember days to various regions and the different needs of the people, the conferences of bishops should arrange the time and plan of their celebration.
- Consequently, the competent authority should lay down norms, in view of local conditions, on extending such celebrations over one or several days and on repeating them during the year.
- On each day of these celebrations the Mass should be one of the votive Masses for various needs and occasions that is best suited to the intentions of the petitioners.
They may appear in some calendars as "days of prayer for peace".
They were made optional by churches of the Anglican Communion in 1976. In the Episcopal Church, the September Ember Days are still (optionally) observed on the Wednesday, Friday, and Saturday after Holy Cross Day, so that if September 14 is a Tuesday, the Ember Days fall on September 15, 17, and 18, a week before the dates observed by the Roman Catholic Church.
Some Lutheran church calendars continue the observation of Ember and Rogation days though the practice has diminished over the past century.
Ordination of clergy 
The present rule which fixes the ordination of clergy in the Ember weeks was set in documents traditionally associated with Pope Gelasius I (492 - 496). In the earlier church ordinations took place whenever necessity required. Gelasius is stated to have been the first who limited them to these particular times. The rule once introduced commended itself to the mind of the church, and its observance spread. We find it laid down in the pontificate of Archbishop Ecgbert of York, A.D. 732 - 766, and referred to as a canonical rule in a capitulary of Charlemagne, and it was finally established as a law of the church in the pontificate of Pope Gregory VII, ca 1085.
The English name for these days, "Ember", derives from the Anglo-Saxon ymbren, a circuit or revolution (from ymb, around, and ryne, a course, running), clearly relating to the annual cycle of the year. The occurrence of the Anglo-Saxon compounds ymbren-tid ("Embertide"), ymbren-wucan ("Ember weeks"), ymbren-fisstan ("Ember fasts"), ymbren-dagas ("Ember days") makes this etymology quite certain. The word imbren even makes it into the acts of the "Council of Ænham" (1009): jejunia quatuor tempora quae imbren vocant, "the fasts of the four seasons which are called "imbren'". It corresponds also with Pope Leo the Great's definition, jejunia ecclesiastica per totius anni circulum distributa ("fasts of the church distributed through the whole circuit of the year").
However, others maintain that the term is derived from the Latin quatuor tempora, meaning "four times" (a year), while folk etymology even cites the phrase "may ye remember (the inevitability of death)" as the source. J. M. Neale's Essays of Liturgiology (1863), Chapter X, explains the etymology:
"The Latin name has remained in modern languages, though the contrary is sometimes affirmed, Quatuor Tempora, the Four Times. In French and Italian the term is the same; in Spanish and Portuguese they are simply Temporas. The German converts them into Quatember, and thence, by the easy corruption of dropping the first syllable, a corruption which also takes place in some other words, we get the English Ember. Thus, there is no occasion to seek after an etymology in embers; or with Nelson, to extravagate still further to the noun ymbren, a recurrence, as if all holy seasons did not equally recur. Ember-week in Wales is Welsh: "Wythnos y cydgorian", meaning "the Week of the Processions". In mediæval Germany they were called Weihfasten, Wiegfastan, Wiegefasten, or the like, on the general principle of their sanctity.... We meet with the term Frohnfasten, frohne being the then word for travail. Why they were named foldfasten it is less easy to say."
See also 
- Rogation days
- Perchta (Quatemberca, Kvaternica, Lady of the Ember Days)
- Quarter days
- Cross-quarter day
- Francis Mershman (1913). "Ember Days". Catholic Encyclopedia. New York: Robert Appleton Company.
- Encyclopædia Britannica article Ember days
- 1973 ICEL translation of General Norms for the Liturgical Year and the Calendar, 46-47; for the Latin text see Normae universales de anno liturgico et de calendario
- Article at Bartleby dot com
- 1979 ECUSA Book of Common Prayer, p. 18, accessed 2010-09-01.
- More correctly a synod, convoked by King Ethelred. "Aenham" was identified as "probably Ensham, in Oxfordshire" by Thomas Lathbury, A History of the Convocation of the Church of England 1842:54. The site would have been the Abbey of Eynsham rather than the town.
- Encyclopædia Britannica 1911, s.v. "Ember Days"