Podcast (Hebrew)During the covenant between the pieces, Abraham received a prophecy about what would happen to his descendants many years after his death:
And He said unto Abram: ‘Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years; and also that nation, whom they shall serve, will I judge; and afterward shall they come out with great substance. But thou shalt go to thy fathers in peace; thou shalt be buried in a good old age. And in the fourth generation they shall come back hither; for the iniquity of the Amorite is not yet full.’ (Genesis 15:13–16)
וַיֹּאמֶר לְאַבְרָם יָדֹעַ תֵּדַע כִּי גֵר יִהְיֶה זַרְעֲךָ בְּאֶרֶץ לֹא לָהֶם וַעֲבָדוּם וְעִנּוּ אֹתָם אַרְבַּע מֵאוֹת שָׁנָה. וְגַם אֶת הַגּוֹי אֲשֶׁר יַעֲבֹדוּ דָּן אָנֹכִי וְאַחֲרֵי כֵן יֵצְאוּ בִּרְכֻשׁ גָּדוֹל. וְאַתָּה תָּבוֹא אֶל אֲבֹתֶיךָ בְּשָׁלוֹם תִּקָּבֵר בְּשֵׂיבָה טוֹבָה. וְדוֹר רְבִיעִי יָשׁוּבוּ הֵנָּה כִּי לֹא שָׁלֵם עֲוֹן הָאֱמֹרִי עַד הֵנָּה. (בראשית ט"ו יג-טז)
This familiar prophecy conceals a secret within its folds. To uncover it, we must focus on two details and their relationship: the four hundred years of servitude, and the identification of the generation that would return to the land as the fourth generation.
At the covenant between the pieces, Abraham was told that his descendants would be strangers in a land not their own, serving and suffering there for four hundred years. Yet just before Israel left Egypt, the Torah summarizes their stay as actually lasting 430 years:
Now the time that the children of Israel dwelt in Egypt was four hundred and thirty years. And it came to pass at the end of four hundred and thirty years, even the selfsame day it came to pass, that all the host of the LORD went out from the land of Egypt. (Exodus 12:40–41)
וּמוֹשַׁב בְּנֵי יִשְׂרָאֵל אֲשֶׁר יָשְׁבוּ בְּמִצְרָיִם שְׁלֹשִׁים שָׁנָה וְאַרְבַּע מֵאוֹת שָׁנָה. וַיְהִי מִקֵּץ שְׁלֹשִׁים שָׁנָה וְאַרְבַּע מֵאוֹת שָׁנָה וַיְהִי בְּעֶצֶם הַיּוֹם הַזֶּה יָצְאוּ כָּל צִבְאוֹת ה' מֵאֶרֶץ מִצְרָיִם. (שמות י"ב מ-מא)
At first glance, the difference is insignificant. We might explain that Abraham’s prophecy did not specify decades precisely and therefore gave the round figure of four hundred years. At the Exodus, the Torah’s summary was more exact, specifying 430 years.
Isaac Abarbanel offers this explanation:
Some say that Abraham was told four hundred years, and Scripture did not concern itself with the additional detail of thirty years, because the larger number absorbs the smaller. Here, therefore, Scripture explained the precise number of years as it actually was. (Abarbanel, Exodus 12:21–42)
יש אומרים שלאברהם נאמר ארבע מאות שנה. ולא חשש הכתוב על יתר הפרט של שלושים שנה מפני שהחשבון הגדול בולע את המועט. ולכך ביאר הכתוב כאן מספר השנים המדוקדק על פי אמיתתו. (אברבנאל, שמות י"ב כא-מב)
Alternatively, the verses in Genesis and Exodus may concern different periods. Exodus summarizes Israel’s settlement in Egypt, lasting 430 years. Genesis describes the actual enslavement, beginning some thirty years later and therefore lasting only four hundred years.
To accept this explanation, we must show that enslavement began thirty years after the descent to Egypt. Initially it appears that considerably more time elapsed, since enslavement began only after Joseph and his brothers died, as described at the beginning of Exodus:
And Joseph died, and all his brethren, and all that generation. And the children of Israel were fruitful, and increased abundantly, and multiplied, and waxed exceeding mighty; and the land was filled with them. Now there arose a new king over Egypt, who knew not Joseph. (Exodus 1:6–8)
וַיָּמָת יוֹסֵף וְכָל אֶחָיו וְכֹל הַדּוֹר הַהוּא... וַיָּקָם מֶלֶךְ חָדָשׁ עַל מִצְרָיִם אֲשֶׁר לֹא יָדַע אֶת יוֹסֵף. (שמות א' ו-ח)
Joseph and his brothers died approximately seventy years after Jacob’s family descended to Egypt, not thirty. Joseph was thirty when he stood before Pharaoh and interpreted his dreams (Genesis 41:46). He revealed himself to his brothers after the seven plentiful years and two of the seven famine years (Genesis 45:6). At least nine years therefore passed between his appearance before Pharaoh and his family’s arrival. Joseph was thus about forty when his family came to Egypt. He died at 110 (Genesis 50:26), implying about seventy years between Israel’s descent and his death (110 − 40). Moreover, enslavement did not begin immediately upon Joseph’s and his brothers’ deaths, but after a further period in which their memory was forgotten (Exodus 1:6–8). At least seventy years therefore passed between the descent and enslavement. How can we explain the small thirty-year difference between residence in Egypt and servitude and affliction?
To resolve this, we must understand the period the Torah calls Israel’s residence in Egypt as beginning later than the family’s arrival. Their descent was temporary, intended to survive the famine. At that stage they were sojourners rather than permanent residents. The expression residence (מוֹשַׁב) refers to the period beginning after Joseph and his brothers died. Only then did residence in Goshen become permanent, and only then did the Torah begin counting the 430 years until the Exodus. Adding the seventy years from the descent to Joseph’s death gives five hundred years from arrival to departure. Enslavement began thirty years after that death, once Joseph and his brothers had been forgotten, and lasted four hundred years. This accounts for the thirty-year difference between residence and enslavement.
In conclusion, the difference between the four hundred years in Genesis’s covenant prophecy and the 430 years in Exodus can be explained in two ways. On the first, four hundred is a round number for a period actually lasting 430 years. On the second, these are different, largely overlapping periods. The 430 years are the residence counted from Joseph’s and his brothers’ deaths until the Exodus; the four hundred years are the enslavement beginning some thirty years after their deaths.
The Fourth Generation
Abraham’s prophecy ends:
And in the fourth generation they shall come back hither; for the iniquity of the Amorite is not yet full.’ (Genesis 15:16)
וְדוֹר רְבִיעִי יָשׁוּבוּ הֵנָּה כִּי לֹא שָׁלֵם עֲוֹן הָאֱמֹרִי עַד הֵנָּה. (בראשית ט"ו טז)
What does “fourth generation” mean? From when should the generations be counted? How does it relate to the prophecy’s opening description of four hundred years of servitude and affliction? Are these overlapping measures, so that four hundred years of enslavement equal four generations?
If enslavement began after Joseph and his brothers died, we can count four generations as follows. Kohath, son of Joseph’s brother Levi, belongs to the first enslaved generation. Amram, Kohath’s son, is the second. Aaron, Amram’s son, is the third. Eleazar, Aaron’s son and successor, who entered the land (Joshua 14:1), is the fourth generation returning to Canaan.
Simple as this is, it contains a difficulty. How can four generations cover more than four hundred years? This implies over a century between generations, whereas experience shows that a generation lasts no more than a few decades. Today it is about thirty years; in earlier periods, with younger marriage ages, it was closer to twenty. If a generation spans twenty to forty years, four generations cover eighty to 160 years, far short of four hundred.
Furthermore, the Torah explicitly gives Kohath’s and his descendants’ lifespans. Kohath lived 133 years (Exodus 6:18), Amram 137 (Exodus 6:20), and Aaron was eighty-three when he stood before Pharaoh just before the Exodus (Exodus 7:7). Even if Kohath was born when enslavement began and fathered Amram in his final year, and Amram fathered Moses, Aaron’s younger brother, in his final year, enslavement could last at most 350 years (133 + 137 + 80), fifty short of the covenant’s four hundred. In any case, these assumptions about fatherhood in one’s last year are improbable. The Sages recognized this difficulty and interpreted the stay in Egypt as lasting only 210 years. Yet this does not fit the plain meaning of verses describing roughly four hundred years of residence.
Nahmanides offers a different explanation of the fourth generation. He understands it as referring to the Amorites mentioned at the verse’s end. Reading the verse as a whole, Israel could return only after four Amorite generations, when their guilt would be complete and Israel could dispossess them. By shifting the four generations from Israel to the Amorites, Nahmanides avoids identifying them precisely. He does not, however, solve the basic difficulty of reconciling four hundred years with four generations: an Amorite generation is not a century either.
The principal difficulty with these interpretations is that, even if they could make four generations correspond to four hundred years, it remains unclear why the same period of enslavement is described using two measures: years and generations.
Another direction focuses on the meaning of dor, “generation.” Usually it means a stage in a genealogy, but it has other meanings. Modern Hebrew, for example, borrows it to describe a period or developmental stage: cellular networks are called third, fourth, and fifth generation. Perhaps the prophecy means that Israel would return in the fourth stage of the great process it describes. The verses do indeed describe four stages: before enslavement, enslavement, departure, and return to the land. The first begins with Abraham’s prophecy and ends when enslavement starts, in the distant future after Abraham dies at a good old age (Genesis 15:15). The second is the four hundred years of enslavement (15:13). The third is departure from Egypt after God judges the enslaving nation, with great possessions (15:14). The fourth is entry into the land once Amorite guilt is complete (15:16).
This is possible, but incomplete, because neither the Torah nor the wider Bible unambiguously uses dor to mean a period or stage. The closest instance describes Noah as righteous and blameless in his generations (בְּדֹרֹתָיו; Genesis 6:9), which could mean in the period before the Flood. We therefore need an interpretation that preserves the word’s ordinary biblical meaning while fitting the historical reality that four hundred years contains far more than four generations.
The Number of Generations in Egypt
We have seen that the Torah counts few generations from enslavement to the Exodus and entry into the land. Exodus’s genealogies count five between Jacob’s sons and those who entered Canaan. Ordinarily we assume that these are complete genealogies: Kohath is Levi’s immediate son, Amram is Kohath’s, and so on. But an alternative is that the figures listed are only the prominent members of much longer lineages, and their relationships need not be those of father and son. Many more generations could then have lived during the period of over four hundred years than the four named in the Torah.
Samuel David Luzzatto, Shadal, adopts this approach:
We must necessarily say that Scripture omitted some generations between Kohath and Amram. In Numbers 3:28, Kohath’s descendants numbered 8,600 males from one month old and upward, although he had only four sons who established families. This gives 2,150 descendants for each son. Yet Amram fathered only Aaron, Moses, and Miriam; Moses had only two sons and Aaron four. How could Amram, Izhar, Hebron, and Uzziel each have 2,150 people in the second year after leaving Egypt?
על כרחינו צריכים אנו לומר שהשמיט הכתוב קצת דורות בין קהת לעמרם, כי במדבר ג' כ"ח היו לקהת פקודים במספר כל זכר מבן חדש ומעלה 8,600, ולא היו לו רק ארבעה בנים שהעמידו משפחות. הרי לכל אחד מארבעה בני קהת בנים 2,150; והנה עמרם לא הוליד רק אהרן ומשה ומרים, ומשה לא הוליד רק שני בנים ואהרן ארבעה, ואיך ייתכן שיהיו לעמרם וכן ליצהר ולחברון ועוזיאל 2,150 נפשות בשנה השנית בצאתם מארץ מצרים?We must therefore agree […] that Levi, Kohath, and Amram were not immediately successive generations, but that others came between them. The 430 years of Israel’s residence in Egypt (Exodus 12:40) can then be understood literally, as can Israel’s enormous increase in Egypt, which the Torah does not explicitly describe as miraculous. (Shadal, Exodus 6:20)
לפיכך צריך שנסכים [...] כי לוי, קהת ועמרם לא היו דורות תכופים זה לזה, אך דורות אחרים היו ביניהם, ולפי זה יתיישב כמשמעו מספר שלושים שנה וארבע מאות שנה שישבו בני ישראל במצרים (שמות י"ב מ), ולפי זה יובן עוצם ריבוי בני ישראל במצרים, שלא אמרה תורה שהיה דרך נס ממש. (שד"ל, שמות ו' כ)
Evidence appears in Chronicles, which records genealogies considerably longer than five generations from Jacob’s sons to those entering the land. One especially fascinating example is Joshua son of Nun’s lineage:
And the sons of Ephraim: Shuthelah–and Bered was his son, and Tahath his son, and Eleadah his son, and Tahath his son, and Zabad his son, and Shuthelah his son–and Ezer, and Elead, whom the men of Gath that were born in the land slew, because they came down to take away their cattle. And Ephraim their father mourned many days, and his brethren came to comfort him. And he went in to his wife, and she conceived, and bore a son, and he called his name Beriah, because ait went evil with his house. And his daughter was Sheerah, who built Beth-horon the nether and the upper, and Uzzen-sheerah. And Rephah was his son, and Resheph, and Telah his son, and Tahan his son; Ladan his son, Ammihud his son, Elishama his son; Nun his son, Joshua his son. And their possessions and habitations were Beth-el and the towns thereof, and eastward Naaran, and westward Gezer, with the towns thereof; Shechem also and the towns thereof, unto Aiah and the towns thereof; (I Chronicles 7:20–28)
וּבְנֵי אֶפְרַיִם שׁוּתָלַח וּבֶרֶד בְּנוֹ וְתַחַת בְּנוֹ וְאֶלְעָדָה בְנוֹ וְתַחַת בְּנוֹ. וְזָבָד בְּנוֹ וְשׁוּתֶלַח בְּנוֹ וְעֵזֶר וְאֶלְעָד וַהֲרָגוּם אַנְשֵׁי גַת הַנּוֹלָדִים בָּאָרֶץ כִּי יָרְדו לָקַחַת אֶת מִקְנֵיהֶם. וַיִּתְאַבֵּל אֶפְרַיִם אֲבִיהֶם יָמִים רַבִּים וַיָּבֹאוּ אֶחָיו לְנַחֲמוֹ. וַיָּבֹא אֶל אִשְׁתּוֹ וַתַּהַר וַתֵּלֶד בֵּן וַיִּקְרָא אֶת שְׁמוֹ בְּרִיעָה כִּי בְרָעָה הָיְתָה בְּבֵיתוֹ. וּבִתּוֹ שֶׁאֱרָה וַתִּבֶן אֶת בֵּית חוֹרוֹן הַתַּחְתּוֹן וְאֶת הָעֶלְיוֹן וְאֵת אֻזֵּן שֶׁאֱרָה. וְרֶפַח בְּנוֹ וְרֶשֶׁף וְתֶלַח בְּנו וְתַחַן בְּנוֹ. לַעְדָּן בְּנוֹ עַמִּיהוּד בְּנוֹ אֱלִישָׁמָע בְּנוֹ. נוֹן בְּנוֹ יְהוֹשֻׁעַ בְּנוֹ. וַאֲחֻזָּתָם וּמֹשְׁבוֹתָם בֵּית אֵל וּבְנֹתֶיהָ וְלַמִּזְרָח נַעֲרָן וְלַמַּעֲרָב גֶּזֶר וּבְנֹתֶיהָ וּשְׁכֶם וּבְנֹתֶיהָ עַד עַיָּה וּבְנֹתֶיהָ. (דברי הימים א ז' כ-כח)
At first glance, this account conflicts with the picture in the Torah. Chronicles describes Joseph’s son Ephraim and Ephraim’s children as living in the land of Israel and even founding settlements there. Genesis says Ephraim was born to Joseph in Egypt, and the Torah describes Jacob’s entire family descending to Egypt and returning only after 430 years of residence.
Reconciling this contradiction is beyond this chapter’s scope. What Chronicles does show is that considerably more generations separated those who descended to Egypt from those who returned than the Torah lists. Where the Torah names five generations between Jacob and Eleazar son of Aaron, Chronicles gives eleven or twelve. It is therefore reasonable to say that the Torah’s Jacob–Levi–Kohath–Amram–Aaron–Eleazar lineage skips several unnamed generations, abbreviating a much longer genealogy comparable to that in Chronicles.
There were thus far more than four generations between the descent to Egypt and entry into the land. How, then, should we understand the covenant prophecy’s fourth generation?
At the end of Joshua’s genealogy we find familiar figures: Ammihud–Elishama–Nun–Joshua. The Torah identifies Elishama son of Ammihud as Ephraim’s tribal leader in the second year after the Exodus (Numbers 7:48), presumably one of the tribe’s elders and dignitaries. His grandson Joshua served Moses and is described as a young man (נַעַר; Exodus 33:11). Joshua was selected for the military task of spying out the land (Numbers 13:16), so presumably he was of military age, at least twenty. If generations were separated by twenty-five years, Nun would have been about forty-five and Elishama about seventy. Seventy was a very advanced age at the time. Although the Torah describes some extraordinarily long-lived individuals, life expectancy as far as we know was much shorter; these are exceptions, not the rule. We may therefore assume that Ammihud, Elishama’s father, was no longer alive at the Exodus, since he would have been over ninety-five. One further detail is crucial: although Joshua led Israel into Canaan, his generation, the wilderness generation, died in the wilderness. The generation that entered was that of his children, not his own.
The prophecy may therefore refer not, as commonly assumed, to the fourth generation of Jacob’s children who descended to Egypt, but to the fourth generation among Israelites who left Egypt. The first departing generation is Elishama’s, representing the community’s elders and leaders. The second is Nun’s, and the third Joshua’s. All three were sentenced to die in the wilderness following the spies’ sin. Their children, the fourth generation among those who departed, entered the land. It is to them that the prophecy refers.
This interpretation is the secret mentioned at the chapter’s beginning. The covenant prophecy anticipates the spies’ sin and the wilderness generation’s death, determining that only the fourth generation among those leaving Egypt, their children, would enter the land. The idea that forty years of wandering, and even the unplanned eastern approach to the land, were foreknown emerges elsewhere in the Torah, as I will show in “Jacob’s Burial Journey.”
Although the forty years of wandering were punishment for the spies’ sin, the punishment reflected a simple reality. The nation of slaves that left Egypt was not ready to enter the land. They could not take their fate into their own hands and conquer it. They needed forty years in the wilderness and a change of generations to shed a slave mentality and become a free people. The spies’ sin, which prevented immediate entry, was therefore foreseeable and unavoidable. The resulting process of nearly forty years of wandering until they were ready was necessary.
The covenant prophecy indeed describes four stages: before enslavement, enslavement, departure, and return. But departure is not a single event: like the other stages, it is a period, a long transition between Egyptian servitude and entry into the land. This was not a journey of a few days accidentally extended to forty years because of the spies’ sin. It was a necessary preparation, at whose end only the fourth generation among those who left Egypt would be ready to return and inherit the promised land.
