Because calendars are culturally constructed systems, there are several important differences between the modern calendar and the calendars used in biblical times. When dealing with ancient Jewish and early Christian sources, we can reconstruct complete calendar systems. However, the Bible itself, written over many centuries, employs several calendar systems and systems of dating. No single normative calendar system emerges from biblical materials. Nevertheless, many aspects of life in biblical Israel depended on the use of calendars, which regulated religious festivals, agricultural activity, various aspects of the legal system, and the recording of historical events.

Measurement of Time in Antiquity

There were several methods of reckoning time in antiquity. Some units of time corresponded to the observation of celestial phenomena (see Gen. 1:14), such as the rising and setting of the sun (defining the day), the waxing and waning of the moon (the lunar month), the ascension of the sun in the sky at noon (the solar year). Other measurements of time were defined by the agricultural cycle, including planting and the beginning and end of the harvest (see Exod. 23:16; Ruth 1:22). An agricultural scheme serves as the basis of the Gezer Calendar, an important archaeological object of the tenth century BC unearthed about thirty miles northwest of Jerusalem. The Gezer Calendar divides the year into eight periods of one or two months, each of which corresponds to the planting, tending, and harvest of various crops. Still other units of time, such as the seven-day week and the lunisolar year (see below), were derived by counting or calculation and did not correspond to any observable celestial or terrestrial phenomena.

The division of days into hours and minutes is possible in modern times because of mechanical and electronic timepieces. Without these devices, divisions of time shorter than the day would have been approximations at best. Biblical texts refer to dawn, morning, noon, evening, night, and midnight. In NT times, the twelve daylight hours were numbered (Matt. 27:45; John 11:9). There was also a system of dividing the night into “watches,” attested in both the NT and the OT.

The Month and the Year in the Bible

The Hebrew words for “month” are related to the words for “moon” and “new” (i.e., the “new moon”), which suggests that the ancient Israelite month was a lunar month corresponding to the waxing and waning of the moon over a period of twenty-nine or thirty days. The Bible refers to numbered days in each month, as high as the twenty-seventh day.

There are several systems of naming the months in the Bible. Four “Canaanite” month names appear in the OT: Aviv (the first month), Ziv (the second), Ethanim (the seventh), and Bul (the eighth). Because of the infrequent use of these names, some scholars have questioned whether this system was in widespread use in ancient Israel. The names probably are derived from agricultural terms.

In many cases the months are simply numbered. In this system, the first month began in the spring season. According to biblical narrative, this way of reckoning the beginning of the year was commanded to Moses at the time of the exodus (Exod. 12:1). However, the Bible applies this scheme to events much earlier, as in the story of the flood of Noah, which began in the second month (Gen. 7:11), and scholars have associated the numerical system of months with late biblical sources, around the time of the exile. The system may have come into use around that time and replaced an older system.

In some late biblical texts Babylonian month names are adopted, including Nisan (the first month), Sivan (the third), Elul (the sixth), Chislev (the ninth), Tebet (the tenth), Shebat (the eleventh), and Adar (the twelfth). Following biblical usage, the Babylonian month names were adopted in the ancient Jewish calendar, which is still in use today.

Based on references to the “twelfth month,” the Israelite year apparently consisted of twelve lunar months. Accordingly, the lunar year consisted of approximately 354 days, which means that it would not have corresponded to the solar year of approximately 365¼ days. The beginning of the year would have drifted between eleven and twelve days each year. Presumably, this would have been an unacceptable situation, given the fact that many of the biblical festivals were both assigned to lunar dates and were correlated to agricultural events. The problem probably was solved through the intercalation of “leap months,” as was the practice in maintaining the later Jewish calendar. The result is a lunisolar calendar, in which the year is composed of twelve lunar months and is corrected relative to the solar year by the periodic addition of a second Adar (Adar II) seven times in every nineteen-year period. The Bible does not mention this procedure or identify who was responsible for maintaining the calendar in ancient Israel.

Biblical Dates

Modern systems of absolute dating, in which all years are numbered relative to a single historical reference point—for example, the birth of Jesus (Anno Domini), the journey of Muhammad in AD 622 (Anno Hegira 1) from Mecca to Medina in Islamic culture, and the creation of the world (Anno Mundi) in Jewish tradition—were unparalleled in biblical times. Instead, events were usually dated relative to the reigns of kings, Israelite or otherwise. For example, the accession of Abijah is dated to the eighteenth year of Jeroboam’s reign (1 Kings 15:1), and the proclamation of Cyrus is dated to his first regnal year (Ezra 1:1). In other cases, events were dated relative to important historical events. The beginning of Amos’s career as prophet is dated to “two years before the earthquake” (Amos 1:1), and Exod. 12:41 dates the departure from Egypt to the 430th year of the captivity. In other instances, the fixed points on which relative dates are based cannot be determined. The beginning of Ezekiel’s career as a prophet is dated to the otherwise unspecified “thirtieth year” (Ezek. 1:1). The verse may simply refer to Ezekiel’s age.

The same practices of dating events are followed in the NT. The birth of John the Baptist is dated to “the time of Herod king of Judea” (Luke 1:5). The census of Caesar Augustus is identified as “the first census that took place while Quirinius was governor of Syria” (Luke 2:2). As in the OT, such formulas presuppose that the reader has a basic awareness of the succession and reigns of kings and emperors—an advantage lost to modern interpreters, who continue to debate the absolute dating of these events. Perhaps analogously to Ezek. 1:1, the beginning of Jesus’ ministry is dated to his thirtieth year of age (Luke 3:23). Other events and persons reported in the NT can be correlated to extrabiblical historical records to establish absolute dates for biblical events (e.g., the death of Herod Agrippa I in AD 44 [Acts 12:23]). These are distinct from instances in which biblical authors are making a conscious effort to provide dates intelligible to their readers. In contrast to OT historical narrative, for the most part, the NT shows little interest in dating events in its narrative, even according to ancient conventions of relative dating.

The Jubilee was a year of rest after seven cycles of Sabbatical Years (Lev. 25:8–55). The Israelites were to sound the ram’s horn on the Day of Atonement and consecrate the fiftieth year, proclaiming liberty throughout the land. The fiftieth year was to be a “jubilee” (Heb. yobel ).

Two principles were essential to the Jubilee practices. The first was that the land belongs to God (Lev. 25:23). The Israelites’ socioeconomic system, rooted in the land, was shaped by their understanding that they were to provide for all members of society from God’s land. The second was the familiar redemption paradigm. God had brought them out of Egypt, delivering them as free people so that they might serve him (25:38–45). Thus, they were not to own land or slaves permanently, since that would reverse the impact of the exodus and create a perpetual underclass. Instead, they were to buy them back, just as God had redeemed his people.

The specific requirements for the Year of Jubilee involved rest for the land, continuing the Sabbatical Year practices. The people were not to sow or harvest. In the Jubilee Year they were to return land and houses to the family or clan of original ownership. The price of any land sold was to be determined by the number of potential crops that the buyer had forthcoming until the next Jubilee. If it was a long time, the price could be set higher. In the interval, if someone had sold family landholdings due to financial stress, the nearest relative could redeem them, or the seller could buy them back personally. In the end, however, the property reverted to the clan ownership in the Jubilee. A house in a walled city could be redeemed for one year. After that, the new owner could keep it permanently because the urban setting was separate from the land. A house in an unwalled city could be redeemed anytime and had to be returned to the original owner at the next Jubilee, since such a city was considered open country. Property of the Levites was always subject to redemption. Any Israelite unable to pay off debts could sell himself, either to a fellow Israelite or to a resident alien. As with the land, the nearest relative or the seller could provide the redemption payment prior to the Jubilee. Failing that, in the Jubilee Hebrew hired workers and their children were to be set free.

There is no direct evidence in the historical books that the Israelites actually practiced the Year of Jubilee. There are echoes of it in Isa. 61:1–7 with the allusions to the release of the prisoner (as in Lev. 25:10) and the inheritance. Jesus cited this passage with reference to his own messianic ministry (Luke 4:16–21), suggesting his affirmation and fulfillment of the Jubilee principles.

Refers to the seventh year, wherein the law was read at the Feast of Tabernacles and debts were canceled (Deut. 15:1–9; 31:10–13). Jubilee was another year of release because slaves were set free and property that had been sold reverted to its original owner (Lev. 25:25–33, 54; 27:24). The NT uses language reminiscent of the year of release and Jubilee to speak about Jesus’ redemptive work (Rom. 6:17–23; 8:1–4; Col. 2:13–14; Heb. 2:14–15).

In biblical Israel, leaven used for making bread was a fermented lump of dough saved from an earlier batch. Like sourdough starter, it was added to a new batch of bread, which rose due to the fermentation process. Although the word “yeast” is found in some translations of the Bible, there is no clear evidence that ancient Israel was familiar with it.

Biblical teaching often views leaven as something to avoid. This may be because fermentation was linked with corruption, which to Israel implied uncleanness. Leaven was prohibited during Passover and the Feast of Unleavened Bread to remind the people of Israel that they left Egypt in haste, with no time for bread to rise (Exod. 12:15–20, 39). Leavened bread was forbidden in burnt offerings (Lev. 2:11). It was allowed, however, when brought as firstfruits, a thank offering, a peace offering, or as a wave offering during the Feast of Weeks (Lev. 2:12; 7:13; 23:17). This was possibly because it would be eaten by the worshipers and priests and not burned on the altar.

In the NT, leaven usually retains its negative connotations. Jesus instructed his disciples to beware the leaven—the teaching—of the Pharisees and the Sadducees (Matt. 16:6–12). Paul taught that the sin of one, like leaven, could corrupt the many (1 Cor. 5:6–8). He also wrote that legalism perverts the gospel just as leaven works through a batch of dough (Gal. 5:9). Positively, Jesus compared the growth of God’s kingdom to leaven, which invisibly spreads through a large quantity of dough (Matt. 13:33).

A color noted in medical diagnoses and in describing gold in the OT. The presence of thin, yellowish hair is an indication of leprous or infectious disease (Lev. 13:30, 32, 36). Gold-plating on the wings of a dove is represented as “yellow gold” (KJV) or “green gold” (NRSV) in Ps. 68:13 (NIV: “shining gold”). See also Colors.

Known as the Tetragrammaton (“four letters”), these four consonants comprise the personal name of God. Most English versions gloss this name in small capital letters as “Lord” (see Gen. 15:1) or “God” (see Gen. 15:2 KJV, RSV, NRSV, NASB). “Lord” without the small-capital format signifies a title, not a personal name, in Hebrew: ’adonay. In the intertestamental period, reverent Jews became reluctant to speak the divine name, and so they substituted ’adonay or some title for “YHWH.” In the Middle Ages, when vowels were introduced to the Hebrew text, those belonging to ’adonay were inserted into “YHWH,” reminding readers to speak the title rather than the name. English speakers, however, substituting J for the Y, vocalizing W with a V sound (both under the influence of German), and reading the consonants and vowels together, invented from this an artificial word that no ancient had ever pronounced: “Jehovah” (see Gen. 15:2 ASV).

Many derive “YHWH” from the Hebrew verb “to be” (hayah) and understand the meaning of the name to be “He Is,” though this is debated. Such an etymology is found in Exod. 3:13–14, where Moses asked God his name, and God replied, “I am who I am. This is what you are to say to the Israelites: ‘I am has sent me to you.’ ” Passing by Moses on Mount Sinai, God declared the meaning of this name, revealing God’s nature as being compassionate, gracious, patient, loving, forgiving, and just (Exod. 34:5–7). Jesus claims this name for himself in John 8:58: “Before Abraham was born, I am.” Christians baptize in the singular name of the Father, the Son, and the Holy Spirit (Matt. 28:19). See also Lord.

(1) Sometimes transliterated “Yiron” (NASB, RSV, TEV, NET), “Iron” is the name of a town in the tribal inheritance of Naphtali (Josh. 19:38). It is likely to be identified with the modern city of Yaroun, on the border between Israel and Lebanon.

(2) A malleable metal derived from oxide ores that can be worked into wrought iron and steel. The earliest use of iron dates to the late fourth millennium BC. Old Kingdom Egyptian refers to iron as the “metal of heaven,” probably because the earliest pieces of iron were derived from meteoric iron. Small quantities of smelted terrestrial iron have been found from the third millennium BC in Egypt, Mesopotamia, and Anatolia. Due to technological advancements and economic factors, iron gradually supplanted bronze as the main utilitarian metal in the Levant by the Iron Age (1200–586 BC).

Iron could be mined or found on the surface (Deut. 8:9), but it had to be heated and hammered to remove its impurities. Wrought iron was softer than hardened bronze, but through carburization, tempering, and quenching, iron became stronger and could hold an edge better than bronze. Since ancient furnaces could not get hot enough to liquefy iron, it could not be cast into molds.

The Bible makes several general references to the mining, smelting, and use of iron (Job 28:1; Isa. 44:12; Ezek. 22:20; Sir. 38:28). Genesis attributes the beginning of ironworking and other crafts to the legendary descendants of Cain (Gen. 4:22). The shift in dominance from bronze to iron in the late second millennium BC may have been due either to an international shortage of copper or a more localized shortage of the wood required for the fuel-intensive production of bronze. In Bible times, iron was forged (Isa. 44:12) rather than cast, as the high temperatures necessary to melt iron could not be achieved before the modern industrial age. Biblical references to iron furnaces pertain to smelting (Ezek. 22:20). While one passage describes the richness of the land of Canaan where, among other things, “rocks are iron” (Deut. 8:9), other passages associate ironworking with Egypt (Deut. 4:20; 1 Kings 8:51; Jer. 11:4) or Mesopotamia (Jer. 15:12). The Israelites perhaps lacked the skills to work in iron, as is suggested by the facts that ironworkers had to be brought into the country (2 Chron. 2:14) and at one point the Israelites were dependent on a Philistine monopoly on blacksmithing (1 Sam. 13:21).

Iron was used widely to make many different types of objects, including axes (Deut. 19:5; 2 Sam. 12:31; 2 Kings 6:5), tools for dressing stone (though this is prohibited for the making of altars [Deut. 27:5; Josh. 8:31]) and for engraving stone (Job 19:24; Jer. 17:1), yokes (Deut. 28:48; Jer. 28:13), shackles or chains (Pss. 105:18; 107:10; 149:8), pans (Ezek. 4:3), sharpening tools (Prov. 27:17; Eccles. 10:10), weapons (Num. 35:16; Job 20:24; Ps. 2:9), gate or door bolts (Deut. 33:25; Ps. 107:16), nails (1 Chron. 22:3), chariots (referring only to a part of the axle assembly rather than the entire vehicle [Josh. 17:16; Judg. 1:19]), otherwise unspecified vessels or implements (Josh. 6:19), and agricultural implements (1 Chron. 20:3; Amos 1:3 [archaeologists have also found plow points and other iron tools]). Amos 1:3 may also refer to the use of iron tools as instruments of torture in wartime. Among the uses of iron that may have been considered unusual for the time were for a bed frame (Deut. 3:11) and for horns (1 Kings 22:11).

Iron was valuable enough to be listed in lists of plunder and treasure, alongside gold and silver (Num. 31:22; Josh. 6:19; 1 Chron. 22:14). It was taken from Jericho and dedicated to God’s treasury (Josh. 6:24). David collected large quantities of iron to construct the temple; however, none of the stones for the temple or altar were cut with iron tools on-site (1 Kings 6:7). Iron was an internationally traded commodity (Ezek. 27:19). It was less valuable than gold, silver, and bronze (1 Chron. 29:7; Isa. 60:17; Dan. 2:33–35) but more valuable than lead and tin (Ezek. 22:20; 27:12).

Iron was a symbol of superlative strength (Job 40:18) and, in the moral realm, of stubbornness or rebelliousness (Isa. 48:4). The fiery smelting process represented testing, oppression, wrath, suffering, and drought (Lev. 26:19; Deut. 4:20; 1 Kings 8:51; Jer. 11:4; Ezek. 22:18–20). In contrast to untarnished gold, the corrosive oxidation of iron symbolized corruption (Jer. 6:28).

A wooden crosspiece fastened to the neck and shoulders of one or, more often, two animals (e.g., 1 Sam. 6:7) to facilitate labor. Yokes were also used by individuals to balance a load suspended from the shoulders (Num. 4:10, 12; 13:23). As such, the yoke also functioned as a symbol of subjection (Gen. 27:40; Lev. 26:13; Deut. 28:48; Jer. 27:2–7; Gal. 5:1; 1 Tim. 6:1), sometimes of joint labor (2 Cor. 6:14; Phil. 4:3), and is closely associated with pairs of animals (Luke 14:19; 1 Sam. 11:7). See also Weights and Measures.