In this case “ember” has nothing to do with fire.
Some say it’s a corruption of the Latin “Quatuor Tempora”,
meaning “four times” because they occur four times a year
(at the beginning of each of the four seasons).
Others consider it a variation of the Old English “ymber”.
“Thus says the Lord of hosts:
The fast of the fourth month, and the fast of the fifth,
and the fast of the seventh, and the fast of the tenth
shall be to the house of Judah, joy, and gladness,
and great solemnities: only love ye truth and peace.”
The Ember Days are times of prayer, fasting and partial abstinence
at the beginning of each of the four seasons–the consecutive Wednesday,
Friday and Saturday after Ash Wednesday, after Pentecost,
after the Exaltation of the Cross (Sept. 14) & after St. Lucy (Dec. 13
–sometimes we miss this feast because it falls on a Sunday,
and since every Sunday is a “little Easter”, Sundays take precedence).
One memory aid was the phrase “ashes, dove, cross, Lucy”.
They were definitely arranged and prescribed for the universal Church
by Pope Gregory VII (1073-1085),
but the practise of setting aside days to sanctify the seasons
goes back to the Early Church–Pope Leo the Great (440-461)
said that it went back to the Apostles themselves.
The partial abstinence means that meat was only taken at one meal of the day
on Ember Wednesdays and Saturdays (Fridays are already meatless).
Wednesday and Friday were selected
because these were the days of penance observed by the Early Church
in place of the Jewish practise of fasting on Tuesdays and Thursdays.
Christians fasted on Wednesdays (the day Christ was betrayed)
and Fridays (in honor of Good Friday).
Saturdays were added as the culmination of the Ember week,
with a procession to St. Peter’s in Rome and an all-night vigil.
The Ember Days are meant to sanctify each season as it arrives.
The purpose of these days of fasting, abstinence and almsgiving,
besides the general one intended by all prayer and fasting,
was to thank God for the gifts of nature,
to teach men to make use of them in moderation,
and to assist the needy.
They are seasonal “days of recollection”, or spiritual renewal,
as well as days to ask God to bless the fruits of the earth
and to thank Him for the blessings He has provided.
They give us time to reflect on the beauty of the seasons
and what they can teach us about God and Heaven.
St. Thomas Aquinas tells us that “the beauty of spring,
the brightness of summer, the plenty of autumn, the rest of winter”
are foreshadowings of the wonders of our eternal home.
The Saturday of the Embers Days is the most important–
at one time an all night vigil was held at the end of the Ember Days
from Saturday night to the following Sunday morning.
Each of the three days has its own emphasis:
Ember Wednesdays are dedicated to Mary; they are always “Mary’s Day”.
All four ember Wednesdays were celebrated in the station church St. Mary Major.
Wednesday, devoted to our Lady, is a day of reflection and spiritual orientation.
All four Ember Fridays take place in the stational church
of the Basilica of the Apostles.
I like how Father Parsch puts it: “Ember Friday is the liturgy’s ‘Yom Kippur.’”
Friday emphasizes conversion and penance.
All the Ember Saturdays take place in the stational church of St. Peter.
Saturday is a preview of Easter,
and it marks the renewal of our baptismal covenant.
–Family in Feast and Feria
At first the ordinations of the sacred ministers in Rome
took place only in the month of December —
when, that is to say, the Christian family at the approach of the Christmas festival
made an offering, as it were, to God, by a solemn three day’s fast…
taking this opportunity to beg the bestowal of his gifts
upon those whom the Holy Ghost had chosen to carry on the work of the Apostles
to guide the flock of Jesus Christ…
In the old sacramentaries the Ember Saturdays
are often called the Saturdays of the Twelve Lessons…
Long before the monks transplanted from Egypt
the form of the psalmodic vigil in use in those monasteries
and introduced it into the liturgy of the Roman basilicas,
the night watch of the Church in Rome
adopted a complete intermingling of twelve lessons, repeated in Latin and Greek…
and alternated with the responsorial chant of the famous morning Hymns
and with the collects of the priest…
At the end of the vigils, at daybreak, the canticle of the three youths of Bablyon, commonly called the Benedictiones, brought the psalmody to a close,
and served to fill in the time between the vigiliary office
and the offering of the eucharistic sacrifice.
Before, however, the sacred gifts were brought to the altar,
the ordination of the new ministers took place…
We know as a matter of fact that it was St. Gregory
who shortened the primitive vigiliary rite,
which originally included the recitation of twelve lessons in Greek as well as in Latin.
The holy Pontiff reduced these by half, but such was the force of habit
that outside the immediate surroundings of the papal Curia
not only did the old name of Saturday of the Twelve Lessons,
already given to the Ember Saturdays, remain unchanged, but,
thanks to the Gelasian Sacramentary,
which was in use in very many places in France and elsewhere,
the famous twelve lessons of the Easter vigil also escaped destruction.
–Blessed Cardinal Schuster, The Sacramentary
Since ordinations were traditionally held on Ember Saturdays,
they’re good days to pray for vocations and for ordinations.
Also, each season has its own emphasis (based on Mediterranean harvests)
1. In spring, during the week after Ash Wednesday,
to give thanks for the rebirth of nature and for the gift of light.
2. In summer, within the octave of Pentecost,
to give thanks for the wheat crop.
3. In autumn, beginning on the Wednesday
immediately after the Feast of the Exaltation of the Holy Cross (September 14),
to give thanks for the grape harvest.
4. In winter, within the week following the Feast of St. Lucy (December 13),
during the third week of Advent,
to give thanks for the olive crop.
–Family in Feast and Feria
This corresponds with the scriptural expression of the totality of divine blessing:
the grain, the wine and the oil
(see Joel 2:19, Hosea 2:22, Deuteronomy 11:14, Jeremiah 31:12, etc.).
You raise grass for the cattle,
and vegetation for men’s use,
producing bread from the earth,
and wine to gladden men’s hearts,
so that their faces gleam with oil,
and bread fortifies the hearts of men.
The fruits of these harvests, wheat, wine, and oil,
have been put to the highest possible use in the liturgy of the Church,
for she uses them sacramentally, that is,
as external signs of the inner grace imparted through her sacraments.
She uses bread and wine at the holy sacrifice of the Mass and at Holy Communion;
she uses oil at Baptism, Confirmation, Holy Orders, Extreme Unction,
and for many of her sacramentals
(baptismal water, blessing of bells, churches, chalices, etc.).
–Family in Feast and Feria
Sermons by St. Leo the Great about the Ember Days can be found here.
(for the winter Ember Days sermons, search for “tenth month”).
He really emphasizes the importance of almsgiving!
With the revision of the liturgical calendar in 1969,
the Vatican left the celebration of Ember Days
up to the discretion of each national conference of bishops.
In the United States,
the bishops’ conference has decided not to celebrate them,
but many dioceses around the world still do.
Even in the U.S., individual Catholics, a number of Religious orders
and most Latin Mass organizations still observe the Ember Days.
May God bless your sanctification of the season!