CALENDAR, a system of measuring time by reference to recurring phenomena or to computed intervals.
Outline
I. Origins and development
A. Origins. The calendar is one of the oldest forms of applied science; its purpose is not merely to keep records, but also to predict developments. In a community whose livelihood depends on seasonal opportunities (e.g., for agriculture, or hunting, where the game moves with the seasons), one must know the right time for action.
Religion added incentives for prediction, in the general belief that sacrifices were required to insure success in agriculture or hunting; and success called for thanksgiving as well as joy. In true religion as in false, observances must be scheduled to enable the community to unite in fellowship, or consecration, or desire. It fell to the priests to maintain the calendar, a task certainly beyond the ability of the unskilled. The Samaritan claim was typical (Bowman, VetTest 15 [1965], 120ff.); calculations depended partly on the correct text of instructions, partly on an expertise which only the priests could have.
B. Development. As trade increased, a calendar became an essential basis for contracts. Within the more advanced communities, the functions of administration (esp. fiscal and judicial) needed a calendar to fix periods and systematize records. In government and trade, wider horizons and more sophisticated organization called for more compatible, standardized calendars.
An imperial power might impose its own calendar or adopt that of a conquered civilization. The Pers. conquerors of Babylon first adopted the Babylonian calendar, then imposed it throughout their later empire (Bickerman, p. 24). The Romans found no system in their Gr. dominions which commanded any wide acceptance; but their own calendar was so erratic that, eventually, Julius Caesar carried out a thorough reform. He did this without disturbing the festivals from their places within each month, or removing nominal control from the priests; as Segal says (JSS 6, 74ff.), a calendar which breaks completely with ancient traditions is not likely to survive for long. Caesar’s reconciliation of tradition and science gave Europe a stable solar calendar based on computation, and resolved the tension between conservative and systematizing tendencies.
While there is no absolute need to use a solar year, there are good practical reasons for matching everyday reckoning to the climatic cycle. The history of the calendar is largely concerned with the attempt to reconcile observational and climatic factors; the former proved more complex and subtle than was at first suspected.
II. Natural conditions
A. Weather. Climatic changes (cyclic variations in the weather) control the growth and ripening of the earth’s produce: (1) rainfall promotes growth directly, and causes rivers to appear or rise, sometimes in countries which do not themselves receive appreciable rain; (2) insolation, varying with the sun’s altitude, affects the heat of the earth and hence of the atmosphere; this in turn affects the prevailing winds and the rainfall. All climatic conditions, the seasons, and the growth of crops, depend ultimately on the sun and on the fact that the earth’s axis is not perpendicular to the ecliptic.
In many parts of the world, the heating of the land during the day produces an onshore wind, if meteorological conditions are otherwise stable.
B. Observation.
1. Solar. Daily change in the sun’s meridian altitude corresponds to the climatic cycle. It is possible, but it requires skill and apparatus, to determine the solstices and equinoxes to within a day. The solar or tropic year is approximately 365.24 mean solar days. Since the earth’s orbit is slightly elliptic, the fall equinox comes about 186 days after the spring (vernal) equinox.
2. Lunar. The moon’s phases are readily observed, but less easy to determine precisely, except for the phasis; even here, since the moon moves half a degree eastward (relative to the sun) in each hour, the crescent might be seen in Pal. on a night when it had not appeared in Babylonia; cloud or haze may also hinder observation. The altitude of the crescent varies, partly because of the varying inclination of the ecliptic to the horizon, partly because the moon may be up to five degrees N or S of the sun. The moon’s synodic period (lunation) is about 29.53 days.
3. Stellar. The stars are the most accurate indicators of time; being so far from the earth, they appeared fixed until astronomers could make precise measurements. From the point of view of the man-in-the-field, their unvarying pattern goes through an annual cycle corresponding to the sun’s movement against the stellar backcloth. A constellation appears farther to the W each evening, until it no longer appears before sunset. Soon afterwards, it becomes visible in the E before dawn (heliacal rising) and rises earlier each night until it is again visible at sunset.
From very early times the stellar cycle was associated with the seasons, but only after many centuries did the annual shift become apparent. Precision causes (a) a shift of the solstices and equinoxes with reference to the Zodiac; (b) a shift of the equatorial plane in relation to the ecliptic, so that stars which once rose or culminated at the same time no longer do so.
III. Terminology
A. Biblical terms.
1. Day. Yōm (Akkad. ūmu, day or wind, cf. II A; Phoen., Ugaritic ym); daylight as opposed to night, or the daynight cycle (Gen 1:5); the basic unit of time, used for: (a) short periods of days; (b) occasionally for a longer period, rarely for more than fifty (Gen 7:24; 8:3; Esth 1:4; Ezek 4:5f.; Dan 12:11, the days are symbolic); (c) periods, prob. approximate, using the number “forty”; (d) the period of gestation; (e) a seasonal period (e.g., of harvest); (f) an undefined limited time, esp. a lifetime; (g) elapsed time generally (e.g., Gen 4:3); (h) a year (e.g., Lev 25:29; Num 9:22; 1 Sam 27:7), and in expressions meaning “annual” (“seasonal” according to F. North).
2. Week. Shabua’ (seven-day period) occurs in the OT, mainly in connection with the Feast of Weeks and in the prophecies of Daniel. In the NT, “sabbath” is used as a dating reference and as a period (Luke 6:1). See below, par. V (E.).
3. Month. Yeraḥ (Akkad.) from yāreaḥ, the moon (as a visible object) is used (a) for a lunation; (b) for a specific month; (c) in counting months. Hōḏesh, from hāḏāsh, new, meaning the crescent or the day of its appearance, hence the reference for dating within a month; found throughout the OT as a common synonym for yeraḥ. See New Moon.
4. Season. Mō'ēḏ, time of assembly, appointment; astronomical fixing is mentioned in Genesis 1:14; Psalm 104:19, and may be assumed for festivals (Exod 13:10; 34:18; Lev 23:4; Num 9:2), but would not apply in such contexts as Genesis 17:21; 1 Samuel 13:8. Hosea 2:9, 11 and illustrates the range of meaning. ’ēṭ, time, can refer to any period or point of time, including a recurring natural period (e.g., the rainy season, Lev 26:4; Deut 28:12; etc.). Names of particular seasons are agricultural terms, as qaiṩ, summer (heat); ḥōrep̱, fall (of “gathering” fruit); qāṩir, harvest; also “wheat-” or “barley-harvest”; compare “first-ripe grapes,” Numbers 13:20; mōreh/yōreh, former rain (November); malqōsh, late rain (March).
5. Year. For yāmīm, days, see above (1.h). Shānāh, turning or change, the great cycle which governs all human activity. Connected with it are: T’qūp̱āh, circuit (Ps 19:6), end of period (1 Sam 1:20), of the year (Exod 34:22, at the fall harvest; cf. 2 Chron 24:23); in Judaism, the quarter-days, each of which was the “new year” for a different purpose. Teshūḇāh, return, i.e. of the campaigning season (2 Sam 11:1; 1 Kings 20:22, 26; 2 Chron 36:10).
B. Glossary. Celestial sphere: the imaginary background on which the movements of the heavenly bodies, as seen from the earth, can be traced. Position is defined by degrees of declination from the celestial equator toward the N or S celestial poles (corresponding to latitude), and by right ascension in hours eastward from the vernal equinox, which is the prime reference.
Conjunction: the position of two bodies being in the same direction (longitude) from the earth.
Ecliptic: the apparent path of the sun on the celestial sphere. The plane of the ecliptic is the fundamental reference for the solar system.
Epact (annual): the difference in time between the lunar and solar years (about eleven days).
Epagomenal Days: days added in the calendar to compensate the epact or other such difference; distinct from intercalary days as being part of the calendar and not an interruption of it.
Equinox: point on the celestial sphere where the ecliptic intersects the equator. At the vernal equinox the sun passes from N to S declination.
Golden Number: the remainder from dividing a year date (Anno Domini) by 19, plus 1. This defines the moon’s phases (and all dependent dates) for that year, in accordance with the Metonic cycle.
Heliacal rising: the annual date when a star is seen to rise immediately before dawn. Though not a very precise observation, it was the best way of determining a point in the solar year before accurately calibrated instruments were available.
Intercalation: interruption of calendar sequence to insert an extra unit, ad hoc or regularly.
Longitude: measurement of degrees eastward from the vernal equinox in the ecliptic plane.
Lunation: period between two conjunctions of the moon and the sun (also synodic month).
Metonic Cycle: period of nineteen years, after which the moon’s phases repeat their celestial positions; discovered by the Gr. astronomer Meton in the 5th cent. b.c. The inaccuracy is only one day in twelve cycles (228 years).
Phase (lunar): the appearance of the moon at a given point in its orbit round the earth.
Phasis: the first appearance of the new moon.
Precession: a steady oscillation of the earth’s axis in relation to the ecliptic, in a period of 25,800 years. With reference to the fixed stars, the equinoxes move around the ecliptic, being now 70o from their position in 3000 b.c. The Taurus period denotes the time before about 2500 b.c., when the vernal equinox was in Taurus.
Solstice: time when the sun reaches its maximum declination; position of the sun at this time.
Year: a solar or tropic year is the time in which the sun returns to the vernal equinox. A lunar year is twelve lunations.
Zodiac: the ecliptic divided into twelve zones of 30o for computational purposes, named in Babylonian times after the constellations in the zones.
C. Names of months.
Babylonian
Nisanu
Aiaru
Simanu
Duzu
Abu
Ululu
Tashritu
Arahsamnu
Kislimu
Tebetu
Shabatu
Addaru
Jewish
Nisan
Iyyar
Sivan
Tammuz
Ab
Elul
Tishri
Marhesvan
Kislev
Tebeth
Shebat
Adar
Macedonian
Artemisios
Daisios
Panemos
Loos
Gorpiaios
Hyperberetaios
Dios
Apellaios
Audynaios
Peritios
Dystros
Xanthikos
Julian
Mar/Apr
Apr/May
May/Jun
Jun/Jul
Jul/Aug
Aug/Sep
Sep/Oct
Oct/Nov
Nov/Dec
Dec/Jan
Jan/Feb
Feb/Mar
IV. Calendar systems
A. Hebrew calendars and their derivatives.
1. Old Testament. The agricultural year ended at the harvest of grapes and fruit (Exod 23:16; 34:22; cf. Lev 25:8f.). The seasons had climatic or agricultural names; the Gezer Calendar attempted to correlate these with a system of lunar months, but did not give names to the months. “Canaanite” names, used in official records (1 Kings 6:1, 37f.; 8:2), apparently required interpretation later. The term ḥōḍesh hā'āḅīḅ, month of green ears, is used only in Exodus and Deuteronomy in connection with the Passover (cf. Exod 9:31; Lev 2:14).
Numbering of the months, from the passover month (Exod 12:2), is applied in the Pentateuch and in the few cases arising in the histories (Josh 4:19; 1 Kings 12:32f.; 2 Kings 25; and Esther, where Babylonian names are used but rarely alone; cf. Ezra 6:15; Neh 1:1; 2:1 only). Numbers are used by Jeremiah, Ezekiel, Haggai, and (without “month”) Zechariah. Numbering was important for merchants and administrators, and need not have arisen from Babylonian influence, as Morgenstern (HUCA I) and others assume. For the general population, the festivals marked the annual cycle. These had to follow lunar and solar (agricultural) indications; intercalation must have been practiced, but nothing is said about it in the OT; regulations were not yet possible.
2. Orthodox Jewish. The Jews had a lunisolar calendar on the Babylonian model, intercalating a second Adar and eventually standardizing seven intercalations in nineteen years, though the Mishnaic rules leave the final decision in the hands of the Sanhedrin. According to the tractate Rosh hashshanah, great attention was paid to the observation of the new moon; but it was laid down that there could not be more than seven, nor fewer than five, thirty-day months in any year.
3. Sectarian. a. The Book of Jubilees refers to a calendar of much interest, which abandoned the lunar month for one of thirty days. The year was divided into quarters, each of three months and an epagomenal day (i.e., thirteen weeks), so that all dates fell always on the same day of the week, and festivals never clashed with the sabbath. At the same time, it kept clear of Hel. systems which, like the Babylonian, were tending to a nineteen-year cycle.
The discovery of Jubilees texts at Qumran has revived debate as to whether this calendar could ever have been used in a community. It would have meant abandoning the solar year; no scheme of intercalation seems to avoid compromising its fundamental principles.
b. Qumran. Discrepancy between the orthodox and “covenanter” calendars was a major ground of contention, illustrated by the story that the Wicked Priest affronted the Teacher of Righteousness on what the Teacher, but evidently not the Priest, held to be the Day of Atonement. Qumran seems to have agreed with Jubilees at least in regarding the week as primary, and the calendar as a matter of revelation. Reference to the moon is disputed (Talmon, Scripta Hierosoly mitana 4 [1958]; Bowman PEQ 1959). Kutsch (Vet Test 11) considers intercalation only of weeks, but Vogt (Biblica 39) believes that it was used to reconcile Essene and solar years.
c. Samaritan. The Tolidah shows points of contact with Jubilees; but certain prayers show that the month could begin on the sabbath. Baumgarten (Vet Test 16) regards the calendar as basically lunar.
d. Elephantine. The syncretistic community here, prob. from Northern Israel, used Pers. (i.e., Babylonian) and Egyp. dating, but observed at least the Passover according to Jewish tradition.
4. Theories of development. The Pentateuch does not describe a calendar; it assumes a lunisolar basis. The historical books only give information sporadically; little is known of the observance of festivals under the Judges, or during the ebb and flow of religion under the kings. A series of articles by J. Morgenstern in HUCA demonstrates the scope available to speculation. His theory of an original “Canaanite” solar calendar, replaced in the 6th cent. by one of Babylonian type, was later withdrawn (JBL 83, Vet Test 5) in favor of the pentecontad theory of J. and H. Lewy; both ignore the evidence of the Gezer Calendar and the OT references to the new moon. Derivation of a pentecontad (fifty-day period) from a module of seven, squared and “rounded up,” is suspect both in assumptions and logic (fifty is not “round” unless a base other than seven is already used). Segal (Vet Test 7) points out that natural events rather than computed intervals must dominate the calendar of an agricultural people.
In HUCA XXI, Morgenstern redefined Solomon’s calendar as lunisolar and “Tyrian” (376f.); after many vicissitudes, the pentecontad was revived by the deuteronomists (433), although they numbered the months ordinally (436). Many inconsistencies reveal the unsound methodology of these theories.
B. Gentile calendars.
1. Mesopotamian. Calendars were developed by each of the principal cities; that of Nippur, adopted by Sargon I, became standard. The text enbu bel arḥim (Nineveh, 7th cent.) is the oldest full account, but some “menologies” of propitious and unlucky days date from the second millennium. The earliest calendars were prob. lunisolar; according to Langdon, intercalation was used to keep the barley harvest in Adar. A cycle of seven intercalations in nineteen years was in use by the 4th cent.; but a 7th cent. prism provides for beginning a year at the new moon nearest the vernal equinox. By the 2nd cent. conjunction and phasis were found by computation.
2. Canaanite. Little is known beyond the names of certain months (Ethanim, Bul as in 1 Kings 6 and 8; Lezib, Hiyyar, see Koffmahn, Biblisch Zeitschrift 10 [1966], 217). Worship of the heavenly bodies figured largely in Phoen. religion, but it does not appear that they worshiped the sun more than the moon, nor can their knowledge of the Zodiac imply that they used a standardized month.
3. Egyptian. The Egyp. year began at the Nile flood, and was divided into four seasons of three months. The heliacal rising of Sirius marked this year; but the official calendar (twelve months of thirty days, and five epagomenal) was allowed to creep forward, rotating through the year in what became known as the “Sothic” (Sirius) cycle.
4. Greek. State calendars were the responsibility of the magistrates; varying use was made of the schemes proposed by astronomers for establishing a regular cycle of intercalation. The Macedonian calendar, known chiefly from its use in Egypt by the Ptolemies, had months of twenty-nine days and thirty, alternately; intercalation was irregular. By 117 b.c., the Egyp. calendar was readopted, using Macedonian month names. The Seleucids used the Babylonian calendar with Macedonian names.
5. Roman. Many features of our calendar are Rom. in origin; the January new year (adopted 53 b.c.), the short February, and the names of the months. The Romans neither observed a lunar month, nor did they master intercalation. Caesar introduced a solar year based on a value of 365 1/4 days, which Hipparchus had already shown to be slightly too large; but as the cumulative error is only a day in a cent., it continues to serve, with the Gregorian adjustment.
V. Some problems
A. The new year. Both spring and fall new years are recognized in the Pentateuch (e.g., Exod 12:2; 34:22), and implied in the historical books. Some have maintained that the spring new year came to Judah with the Babylonians (so Finegan, ss. 67f.; it is a non sequitur that the later use of Babylonian names with the numbers indicates a Babylonian origin of the number-system). Morgenstern sees agricultural grounds for both fall and spring—in his original and later theories respectively.
B. Date of the Passover.
1. Pre-exilic. In the Pentateuch, the Passover is firmly dated on the fourteenth day of the first month; but the lack of any historical reference between Joshua (Josh 5) and Hezekiah (2 Chron 30) has been taken to support the hypothesis that the relevant legislation was postexilic; there are grounds for holding that Hezekiah and Josiah gave a new slant to a familiar observance, making it a pilgrimage rather than a local festival. See J. Wilcoxen, Biblical Research 8 (1963), for a review.
2. The Last Supper (Matt 26:17; Mark 14:12; Luke 22:7) was eaten as a passover; John 18:28 indicates that the Jews had not yet eaten it. Discoveries at Qumran, while not directly relevant, open the possibility of differences of practice within Judaism, particularly when a feast fell on the eve of a sabbath.
C. Fall observances. The Day of Atonement (Exod 30:10; Lev 16) is not mentioned in Kings, nor, more surprisingly, in Nehemiah. A later origin has therefore been supposed, but this conclusion is not inevitable, in view of the general ignorance of the law even in Ezra’s time.
Morgenstern (HUCA I, 22f.) argues from Exodus 23:16; 34:22; Deuteronomy 31:10; that the harvest festival formerly preceded New Year’s Day; but this rests on too strict an interpretation. It would be more natural to hold such a festival at full moon.
D. The northern kingdom. Jeroboam I instituted a feast at Bethel on the fifteenth of the eighth month. This may well reflect the later harvest in the N; and if he, in fact, altered the calendar by one lunar month, this may partly explain the second month Passover of Hezekiah when he was canvassing support in Israel (Talmon, Vet Test 8).
E. The Sabbath. Shabbāt (pause, rest) was prob. not derived from sheḇa’ (seven). A cognate Akkad. sapattu denoted the fifteenth of a month, though it may have been used earlier for the epagomenal period (Lewy, HUCA XVII, 78ff.); the 7th, 14th and 28th, though esp. marked, were not restdays in our sense; cf. Langdon p. 83. See Sabbath.
Bibliography B. Landsberger, Der Kult. Kalendar (1915); P. Nilsson, Primitive Time Reckoning (1920); J. Morgenstern, HUCA I (1924), 13-78; G. Dalman, Arbeit u. Sitte I (1927); S. Langdon, Babylonian Menologies (1933); J. and H. Lewy, HUCA 17 (1941), 1-152; J. Morgenstern, HUCA 20 (1947), 1-36, 21 (1948), 365-496; R. Parker, Calendars of Ancient Egypt (1950); A. Jaubert, Vet Test 3 (1953), 250-264; S. Horn and L. Wood, JNES 13 (1954), 1-20; R. Parker, JNES 14 (1955), 271ff.; J. Morgenstern, Vet Test 5 (1955), 35-76; R. North, Biblica 36 (1955), 82-201; J. Obermann, JBL 75 (1956), 285-297; O. Neugebauer, Exact Sciences in Antiquity2 (1957); A. Jaubert, Vet Test 7 (1957), 35-61; J. Segal, ibid., 250-307; E. Vogt, Biblica 39 (1958), 72-77; S. Talmon, Vet Test 8 (1958), 48-74; E. Auerbach, ibid., 337-343, Vet Test 9 (1959), 113-121; J. Bowman, PEQ (1959), 23-37; E. Kutsch, Vet Test 11 (1961), 39-47; F. North, ibid., 446-448; J. Segal, JSS 6 (1961), 74-94; B. Rahtjen, PEQ (1961), 70-72; S. Talmon, JAOS 83 (1963), 177-187; J. Morgenstern, JBL 83 (1964), 109-18; W. Hartner, JNES 24 (1965), 1-16; J. Baumgarten, Vet Test 16 (1966), 277-286; H. Stroes, ibid., 460-475; E. Bickerman, Chronology of the Ancient World (1968).