The Etymologies of Isidore of Seville - Pot-pourri

Church locates the moon of the first month (i.e. of the
Roman calendar’s year) from March 5 through April 3,
and if the fifteenth day of the new moon should fall
on a Sunday, Easter Day is moved forward to the next
Sunday. 20.TheGreekChurchobserves the moon of the
first month from March 8 through April 5, andifthe
fifteenth day of the new moon should fall on a Sunday,
they celebrate holy Easter then. Dissension of this kind
between the two camps confuses the Easter liturgy.
21. Ayear that has only twelve lunar months, that is,
354 days, is called ‘common.’ It is called common (communis)because
often two occur so ‘connected together’
(coniunctus)that they immediately follow one another in
the (table for calculating the) Easter celebration – for an
embolismic (i.e. intercalated) year always occurs alone.
22.Anembolismic (embolismus)year has thirteen lunar
months, that is, 384 days. That year was prophetically
revealed to the holy Moses; in an embolismic year those
who lived long ago were ordered to celebrate the pasch
in the second month. 23. Further ‘embolism’ is a Greek
term that is translated ‘further addition’ (superaugmentum)inLatin
because it fills out the count of days of the
common years, in which eleven lunar days are observed
to be missing. 24. Moreover, embolismic and common
years are found in this way. If there have been 384 days
from the fourteenth day of the new moon of one Easter
Day to the fourteenth day of its successor, the year is
embolismic; if 354, common.
25.The‘bissextus’ is the day added every four years, for
in each year it grows a quarter of a whole unit, but when
it has completed a unit in the fourth year, the bissextile
day is made. 26. Itiscalled the bissextus because twice
six (bis sexies) reckoned up makes a whole unit (i.e. of
the twelve ounces in a Roman pound), which is one
day – just as a quarter-unit (quadrans) isreckonedup
by four times (quater) –because a bissextus is how far
the sun goes beyond the course of the days in the year,
[or because it is not able to be intercalated in its own
year unless you compute ‘twice the sixth’ (bis sextus)day
before the nones of March, that is, both with the first
day as the sixth day before the nones of March and, with
the bissextus added, with the second day repeated as the
sixth day before the nones of March]. 27. Further, from
the sixth day before the nones of March through the day
before the Kalends of January the bissextus is taken into
account in the course of the moon, and afterwards it is
removed.
The Etymologies VI.xvii.20–xviii.5 145
28.Intercalary (intercalaris)daysare so called because
they are interposed (interponere) sothatthereckoning
of the sun and the moon may be reconciled, for calare
means “pose,” and intercalare means “interpose.” 29.
What Greeks call ‘epacts’ (epacta) the Latins call ‘annual
lunar additions,’ which run through a cycle from eleven
to thirty days. The Egyptians add epacts to make the
lunar measurement equal to the reckoning of the sun.
30.Forthe moon in its course is known to shine twentynine
and a half days, so that there are 354 (i.e. 12 × 29.5)
days in a lunar year; there remain in the course of a solar
year eleven days, which the Egyptians add (adicere). 31.
Hence they are called additions (adiectio). Without these
epacts you would not find what point of the lunar cycle
corresponds to a given year and month and day. Those
epacts are always added on March 21,onthe same day of
the moon that falls on that date. 32. Thereare nineteen
years in the (Metonic) cycle, but when the epacts add
up to twenty-nine, which is in the nineteenth year of the
cycle, at that point you do not add eleven epacts to the
twenty-nine in the following year, such that you would
get ten after subtracting thirty, but you start again with
eleven.
xviii. The other liturgical feasts (De reliquis festivitatibus)
1. A‘festal celebration’ (festivitas) issocalled
from ‘festal days’ (festus dies), as if the word were festiditas,
because during those days only sacred activities
are carried out. The contrary to these are court-days
(fasti), on which the law ‘speaks’ (fari, ppl. fatus), that
is, is pronounced. A ‘solemn feast’ (sollemnitas) isso
called from its holy rites, a day adopted in such a way
that for religious reasons it ought not to be changed.
It is named from ‘customary’ (solitus), that is, firm and
solid (solidus), [or because it is customarily (solere)performed
in the church year]. 2. Acelebration (celebritas)
moreover is so called because during it earthly
activity is not carried out, but only celestial (caelestis)
activities.
3.EasterDayisthefirst of all the feasts; we have spoken
of thistermabove.4. LikeEasterDay, Pentecost
was a feast day among the Hebrews, because it was celebrated
five tens of days after Easter Day – whence it takes
its name, for means “five” in Greek. On that day
according to the Law the ‘loaves of proposition’ would
be offered from the new crops (Exodus 25:30,etc.). 5.The
jubilee year in the Old Testament adumbrated this, and