Shemot - "They multiplied and became mighty"
A. THE LENGTH OF THE EGYPTIAN EXILE
"The sojourning of Benei Yisrael which they dwelled in Egypt was four hundred and thirty years" (12:40)
All the midrashim of the Tannaim, and all the commentators, align themselves with the Septuagint, which contradicts the literal meaning of the verse - i.e., that this period dates back to the descent of Yaakov and his family to Egypt; they maintain that the 430 years began somewhere during the time of Avraham. The author of the Seder Olam, Rashi, and their followers claim that it started at the 'berit bein ha-betarim"; Ramban maintains that it began with the birth of Yitzchak, while Ibn Ezra and others opine that we count this period from Avraham's departure from Ur Kasdim.
All of these opinions "shorten" the Egyptian exile by about two hundred years, fixing its length at 210, 215, 240 years, or the suchlike.
All of these commentaries share the same single reason for their forced interpretation of the verse. The succession of generations of Benei Yisrael, from those who descended to Egypt until those who departed from there, makes it impossible to understand the verse literally - that the exile lasted four hundred years or more.
B. "THE FOURTH GENERATION WILL RETURN HERE"
The succession of the generations is listed in the Torah through the genealogy of various families, and especially the three families of the Tribe of Yehuda (Divrei ha-Yamim I 2):
a. Chetzron was among those who went down to Egypt (Bereishit 46:12) - Ram - Aminadav - Nachshon, who was the prince of Yehuda at the inauguration of the Mishkan (Bamidbar 7:12).
b. Chetzron - Kalev - Hur, one of the leaders of the nation at the time of the Exodus (Shemot 17:12) .
c. Chetzron - Seguv - Yair, who conquered the north of Gilad (Bamidbar 32:41).
Such a short list of generations could not conceivably have covered 430 years. Proof of this difficulty may be brought from the list of generations of the tribe of Levi, which appears in next week's parasha (6:16-26) and specifies the lifespan of each of the generations. Rashi quotes this as support for his interpretation: Kehat was among those who went down to Egypt (Bereishit 46:11), he lived 133 years (6:18). His son Amram lived 137 years (6:20), and Moshe was 80 years old at the time of the Exodus.
Admittedly, Yehoshua's genealogy is longer (Divrei ha-Yamim I 7:20-27), spreading easily over 430 years: Ephraim - Beri'a - Refach - Telach - Tachan - Ladan - Amihud - Elishama - Nun - Yehoshua, and Yehoshua was among those who left Egypt. Nevertheless, the proof from the generations of the Tribe of Levi appeared to the commentators to be conclusive, and therefore they opted for the approach described above.
C. "THEY WERE FRUITFUL AND MULTIPLIED GREATLY" – HOW?
We have summarized the view of all the commentaries, but there is a single exception - Shadal's commentary on the Torah. He insists that the Egyptian exile lasted just as the verse says - 430 years . To his view, the list of generations cannot be used as a proof, for it is possible that the Torah leaves out some of them, listing only the important ones. Kehat, for example, is said to have borne Amram - but perhaps there were several generations in between them. An example of this is to be found in the person of Zerubavel, son of Shaltiel (Chaggai 1:12), while in Divrei ha-Yamim I (3:17-19) we discover that he was not his son but rather his grandson .
Shadal's argument against the accepted interpretation seems quite solid. If we assume that the generations of Levi, as they appear in our parasha, are listed in full, then the generation of Kehat - the generation of those who went down to Egypt - included three brothers: Gershon, Kehat and Merari. The generation of Amram, Kehat's son (the generation preceding the Exodus) included Livni, Shim'i, Amram, Yitzhar, Chevron, Uziel, Machli and Mushi - altogether eight.
The number of descendents of Levi at the time of the Exodus is 23,000. How is this possible?
Let us formulate our question differently. The Torah expounds on the astonishing reproduction of the exiles in Egypt. But in the number of children listed for the various families, starting from the generation that went down to Egypt, there appears to be no justification for such hyperbole. If, indeed, the Jewish women in Egypt bore "six children at one time," as the Midrash describes, then why do we read of families with only two or three children? And if there were only four generations, how did the nation then reach the astronomical number of six hundred thousand adult males? We are forced to conclude that Benei Yisrael indeed spent four hundred and thirty years in Egypt, not two hundred and ten.
D. AS 210 (REISH-DALED-VAV) THEY WENT DOWN (REDU)
In order not to unnecessarily increase the Egyptian exile, and in order to maintain an understanding of the matter that accords with that of the Sages, Rashi, the Ramban and the other early commentators, we must find a way to answer Shadal's most relevant question.
I believe that the key to the answer lies in the verse in Sefer Bereishit:
""Now, your two sons who were born to you in the land of Egypt, before I came to you in Egypt - they are mine; Ephraim and Menashe will be mine like Reuven and Shimon. And whoever is born to you, whom you bear after them, will be yours; they shall be called after the name of their brethren in their inheritance." (Bereishit 38:5-6)
It seems to me, according to the literal text, that Yosef had more than two sons. This is what the verse is teaching us when it says, "To Yosef were born two sons BEFORE THE YEARS OF FAMINE BEGAN" (Bereishit 41:50), implying that later on more were born, and it is to these that Yaakov refers when he says, "whom you bear after them." These children are not listed in the genealogy of Yosef's sons, since they join in the inheritance of their brothers, Menashe and Ephraim. Similarly, the Tanakh lists ten sons of King David (six in Chevron - Shmuel II 3:2-5, and four in Jerusalem - Shmuel II 5:14), but Chazal speak of him having four hundred sons; indeed, the verses hint at many more children. Hence the names listed are only the heads of households, with these households numbering not only their sons but also their less important brothers.
It is also possible that many of the descendants of the tribes were killed or died all kinds of terrible deaths during the Egyptian subjugation, and their children joined the families of their fathers' brothers, just as the orphaned Lot joined the family of Avraham. According to this approach, too, only the main heads of households are listed, each representing hundreds and thousands of people, just as each person listed among those who returned from Babylon with Zerubavel represented hundreds or even thousands of family members (see Ezra 2).
Let us examine one example, which may serve to strengthen our assumption. Yaakov went down to Egypt with seventy souls. His sons went down, each with an average of four sons, and these sons in turn also had children. These children are the only ones mentioned in the census conducted in the fortieth year in the desert (Bamidbar 26), but clearly our assumption cannot be that Yaakov's children stopped bearing children from the time they reached Egypt. When they went down to Egypt they were still young - aged forty or a little more, at their peak (compare to the age at which Avraham, Yitzchak and Yaakov bore their children). Is it possible that the thirty-nine year old Yosef had no more children? Or Yehuda, aged forty-three? And why should we assume that Peretz, who was a whole generation younger than his father, stopped having children after Chetzron and Chamol, who went down with him to Egypt? But if he did indeed bear more children, why are the families of these other children not listed in the census of those who inherit the Land, in the fortieth year? We are forced to conclude, then, that those born in Egypt are subsumed under the households of their brethren who went down to Egypt, and that they join in their inheritance.
E. SIX AT ONE TIME
We have not yet arrived at a satisfactory explanation of the unreasonable rate of reproduction, turning seventy souls who came down to Egypt into 600,000 adult males - meaning millions altogether - at the time of the Exodus. If this natural reproduction took place over the course of only three generations, we must assume that every woman bore several hundred children. Hence, it would seem that the genealogy of Yehoshua should serve as the model for our understanding of the structure of Benei Yisrael in Egypt; this genealogy numbers nine generations. To our view, the Tribe of Levi was exceptional in its much smaller number of generations. The reason for its limited population  may have been their custom of marrying late (perhaps wanting to observe the tradition of their forefathers), or because as prophets and Torah scholars (see Shmuel I 2:27 and the midrashim of Chazal) they separated themselves from their wives, and numbered only four generations.
Let us return to Ephraim and the other tribes. If we assume, based on the genealogy of Yehoshua, that a generation was twenty-one years, during the course of 190 years (such that the last generation would be in their twenties at the time of the Exodus) there would have been about nine generations - which is as the genealogy describes.
Accordingly, we may explain Chazal's teaching that the women used to bear "six at one time" (literally, "six from one belly"). This does not mean that the women used to bear sextets; that would be an altogether unnatural phenomenon. What the teaching means is that every mother ("belly") would bear six children during the course of her life. We may assume that, on average, these six children would be three sons and three daughters - and this accords with the size of the families noted in our parasha (keeping in mind that only the sons are listed).
Let us now attempt to calculate of the numbers of Benei Yisrael:
Based on the assumption that the generation that went down to Egypt numbered sixty males who were still of child-bearing age, the next generation would have numbered 180 males; the third generation - 540, the fourth - 1620, the fifth - 4860, the sixth - 14,580, the seventh - 43,760, the eighth - 131,280, and the ninth - some four hundred thousand.
Assuming that it was the seventh, eighth and ninth generations that left Egypt, after about 190 years there were six hundred thousand, and after 210 years - all were aged 20.
The miracle of the reproductive multiplicity in Egypt was therefore a "hidden" miracle - that despite the hardships of Egyptian subjugation and their persecution, women bore six children, and this average did not waver up until the time of the Exodus.
May God fulfill for us His promise in the Torah:
"Be fruitful and multiply; a nation and a community of nations shall emerge from you, and kings will emerge from your loins" (Bereishit 35:11).
 Here I ignore the Midrash which identifies Kalev ben Chetzron as Kalev ben Yefuneh.
 If we add to this his view on the system of historical research regarding the length of the Second Temple period, we find ourselves in the middle of the seventh millennium, which began at the time when Shadal wrote his commentary - some 160 years ago. We shall not elaborate further.
 As to the question arising from the verse, "the fourth generation will return here" - see Rashbam ad loc.
 In our estimation, there were only about ten thousand Levi'im aged twenty and upwards - about a fifth of the average. We base this on a comparison between the number of those aged one month and upwards, and the number of those aged thirty and upwards.
Translated by Kaeren Fish