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Tyndale Open Bible Dictionary

CALENDARS, Ancient and Modern

Systematic arrangements showing the beginning and length of each year and its division into days, weeks, and months. The modern calendar is usually taken for granted. But without a calendar it would be extremely difficult to establish a uniform chronology (that is, a system for arranging events in the time sequence in which they actually happened). Also, accurate prediction of the coming and going of seasons would be impossible.

Before the calendar took on its modern format, it had to progress through a number of developmental stages.

Preview

• Days and Their Divisions

• Astronomy and the Calendar

• Jewish Calendar

• Jewish Festivals

• Conclusion

Days and Their Divisions

The earliest attempt to mark off time was probably the simple counting of days, followed by the subdivision of each day into what eventually became 24 equal parts called hours. Since the Sumerians seem to have originated the measurement of time by minutes, hours, and days, they obviously also knew the narrower meaning of “day,” which for them designated a 12-hour period.

Measurement of time in the days of King Ahaz is illustrated by reference to a sundial (2 Kgs 20:9; Is 38:8). The precise measurement of hours, however, must have been a relatively late practice. Early Europeans, like the ancient Egyptians, placed the beginning of the day at midnight, further dividing the period into two 12-hour segments. In the second century BC the Egyptian astronomer Ptolemy and his disciples devised an astronomically convenient method of calculating each day from high noon, when the sun reached its apex in the heavens. The Roman day began at sunrise, with the second part of the day commencing at sunset.

Astronomy and the Calendar

Ancient peoples constructed their calendars on the basis of their observations of “cycles” of the sun and moon. The solar year is the period of time in which the earth accomplishes a complete revolution in its orbit around the sun.

The life of ancient peoples was closely tied to the changes in temperature and in the relative length of days and nights characteristic of the four seasons. Seasonal changes result from the fact that while the earth is orbiting the sun, it is also rotating on its own axis, tipped at an angle to the plane of its path around the sun. The longest day of the year in the northern hemisphere is called the summer solstice (about June 21 on the modern calendar). At the winter solstice (December 21 or 22) the noonday sun appears lowest (farthest south) and the days are shortest. (In the southern hemisphere summer and winter are reversed by the effect of the earth’s tilt.) Halfway between, at the vernal (spring) equinox about March 21, and the autumnal (fall) equinox about September 23, the sun is directly over the equator and there are as many hours of daylight as of darkness. The term “equinox” is from the Latin words for “equal night.” A solar year could be measured by ancient peoples as the period between two similar solstices or equinoxes.

The solar calendar marks off days by observing the period between consecutive returns of the sun to a similar position above the earth, such as its rising, setting, or highest point at midday. A “day” thus represents one complete rotation of the earth on its own axis, now divided into 24 hours. Since that rotation is not directly related to the earth’s annual orbit around the sun, calendar problems arise because the true solar year does not equal a certain whole number of days but 365 days plus a fraction of a day.

The most significant calendar problems arise when the sun’s motion is not the only factor taken into consideration in marking off a year. Considerable difficulties were encountered in ancient attempts to reconcile solar and lunar periods, especially when subdivisions of the year (months) were made to correspond to the more irregular phases of the moon. The fact that while the moon is orbiting the earth, the earth is orbiting the sun (and rotating at the same time) produces many complications.

The lunar calendar measured time by lunations (a lunation is the interval of time, expressed in days, between two successive new moons). Each lunar month, beginning when the thin crescent of the new moon first becomes visible at dusk, averages just over 29½ days. The moon actually orbits the earth in about 271/3 days. Because the earth is meanwhile moving around the sun, it takes the moon two extra days to come to the same position between the sun and earth and produce a “new moon.”

A lunar year of 12 months was approximately 11 days shorter than the solar year, so additional days were inserted to make up for the difference. The practice of insertion, known as intercalation, was a device common to several lunar calendar systems. The ancient Chinese compensated by adding an intercalary month every 30 years to their calendar, which consisted of 12 months of 29 or 30 days each. The Muslim lunar calendar, still used throughout Islam, also recognized 30 years as a cycle. Beginning with the second year within each cycle, and at subsequent intervals of three years, a “leap year” (a year of abnormal length) is observed. In that framework a leap year comprises 355 days as opposed to the ordinary Muslim year of 354 days. Calculation of the ancient Hebrew year suffered the same problems as other lunar calendars.

Jewish Calendar

It is hard to imagine a people with lives more closely bound to and regulated by the calendar than the people of ancient Israel. The Jewish calendar is dated from what is supposed to have been the Creation: 3,760 years and three months before the Christian era. Accordingly, to find the current year in the Jewish calendar, one must add 3,759 to the date in the Gregorian calendar. The system, however, will not work to the exact month, since the Jewish year (running on the civil calendar) begins in autumn rather than in midwinter.

Months

Most of the 12 months of the postexilic calendar have names adapted from the Babylonians. The months do not correspond to but overlap the months of the Roman calendar.

The names of over half the months are mentioned in the OT: Kislev (Neh 1:1; Zec 7:1; rsv “Chislev”), Tebeth (Est 2:16), Shebat (Zec 1:7), Adar (Est 3:7, 8:12), Nisan (Neh 2:1; Est 3:7), Sivan (Est 8:9), and Elul (Neh 6:15).

Since the Jewish month invariably began with the new moon, at intervals of approximately 29½ days, the Jewish year ran 354 days. No exact information is available to explain how the Jews originally adjusted their inaccurate lunar calendar to synchronize with the actual solar year. Late in Israel’s history an extra month was inserted between Adar and Nisan. That month, sometimes called Veader (“second Adar”), was added seven times within a 19-year cycle (at which time Adar received an extra half day).

The names for the Jewish months as now known come from the period following the return from Babylonia to Palestine. Before the Babylonian exile at least four other names were in use: Abib (Ex 13:4), Ziv (1 Kgs 6:1, 37), Ethanim (8:2), and Bul (6:38). After the Captivity, they were renamed Nisan, Iyyar, Tishri, and Heshvan (originally Marcheshvan), respectively. The preexilic names carried agricultural connotations. For example, Abib signified the month in which the heads of the grain became ripe; Ziv was the month for desert flowers to bloom. An agricultural orientation is apparent in what is evidently the oldest Hebrew calendar, found at Gezer (southeast of Tel Aviv) in 1908 and dating from the 10th century BC. Probably the work of a Jewish schoolboy, the calendar breaks down the year by agricultural activities such as sowing, reaping, pruning, and storage.

Primarily, however, the months were religiously significant to the Jews and enabled them to commemorate the important events of their history. Each month’s beginning was considered holy. To ancient Israel, the moon became a spiritual symbol of the nation itself; the sun eventually became symbolic of the Messiah (Mal 4:2). Since the moon produces no light of its own, the symbolism is especially appropriate: Israel was supposed to reflect the Messiah’s light to the world.

The Jewish calendar remained unchanged during the period between the OT and NT (approximately 400 years) despite an attempt by Hellenistic rulers to introduce a modified lunar month system, presumably of Macedonian origin. According to that calendar, five days were added to the final month of the year, with each of the 12 months containing 30 days. Even then, it only approximated the solar year.

Reckoning of Dates

We know of no era in which the ancient Hebrews recorded dates by citing a month and day. Rather, dates were computed by reference to some significant event such as the accession year of the reigning king. In NT times the Jews continued the OT method of dating events by synchronizing them with events either in their religious calendar or within the secular sphere of the Roman world. Writers of the NT followed the same principle (Lk 1:5; Jn 12:1; Acts 18:12). Only as the calendar reforms of Julius Caesar became embedded in the culture did people change from that long-standing method to a more standardized system.

Jewish Festivals

In addition to keeping the Sabbath, Jews observe seven annual festivals.

1. Passover (14th of Nisan) marks the deliverance from Egypt (the exodus). The first day of Nisan determines the date for Passover. Passover is observed for seven days and encompasses the Feast of Unleavened Bread, an event recalling Israel’s hasty preparation for the flight from Egypt (Ex 12:15). The festival for the firstfruits of the barley harvest immediately follows (Lv 23:10, NLT).

2. Pentecost is celebrated 50 days after Passover. A time of joyful celebration for the people, Pentecost is the Feast of Ingathering of the firstfruits of the wheat harvest (Ex 34:22; Lv 23:15-17).

3. Next in order is New Year’s Day, the beginning of Tishri. The first of Tishri, according to the rabbis, was the day in which the Lord created the world. It is called Rosh Hashanah, “head of the year.”

4. On the 10th of Tishri, Israel’s most solemn day, Yom Kippur (the Day of Atonement), is observed. This holiest of days is known as “the Sabbath of Sabbaths,” and the complex ritual for its observance is set forth in the Bible (Lv 16).

5. Succoth, the Feast of Tabernacles, occupies the 15th through the 22d of Tishri. A largely agricultural festival, it celebrates the ingathering of the autumn harvest. The apostle John referred to it simply as “the feast” (Jn 7:37). The Feast of Tabernacles, sometimes called the Feast of Booths (Shelters), is also a spiritual commemoration; it recalls God’s care over his people throughout Israel’s 40 years in the wilderness (Lv 23:39-43).

6. Of later origin is the Festival of Hanukkah, the Feast of Dedication. It commemorates Judas Maccabeus’s decisive victory over Antiochus Epiphanes and the Syrians 150 years before Christ. Since Malachi, the last of the OT prophets, had passed from the scene long before that event, tradition alone governs the manner in which the occasion is celebrated. On the 25th of Kislev and the following seven days, joyous activities mark the Jewish calendar.

7. Concluding the sacred festivals for the year is Purim, which falls on the 14th and 15th of Adar. The feast, which finds its origin in ancient Persia, commemorates the deliverance brought through Mordecai and Esther when they frustrated Haman’s plot to destroy the Jews (Est 9).

Conclusion

As ancient sundials and modern clocks mark the passage of minutes and hours, a calendar marks the passage of days, weeks, months, years, and even centuries. A uniform, understandable way of measuring the longer units of time aids secular enterprises such as agriculture, business, and government; it is essential to historians and brings unity to the celebration of religious rites. Development of the modern (Gregorian) calendar represents an interaction between the science of astronomy and much historical and religious tradition. The religious significance of the calendar for Christians stems partly from the biblical contrast between God’s timelessness and human mortality (Ps 90). The psalmist asked God to “teach us to number our days that we may get a heart of wisdom” (Ps 90:12, rsv).