Where are the remaining holidays of Tishrei? Is it, as apologists like S.R. Hirsch argue, that the author of Dt. knew of the other holidays but that Pesah, Shevuout, and Sukkot (the 3 festivals mentioned in the Parsha and, indeed, in the whole sefer devarim) have common themes? Or is it that the author of Dt. did not know of or did not approve of the other holidays we now observe?
Let us look at the story of the building of the Temple by Shlomo. There (I Kings Chapter 8) we read (v. 2) "And there assembled to the King Shlomo every man of Israel in the month of the Etanim, on the holiday, this is the 7th month" and then after an account of some serious feasting (v. 62-64) we read (v.65)"And Shlomo made at that time the holiday and all Israel with him, a great congregation from the entrance to Hamat to the Brook of Egypt before YHVH our God, 7 days and 7 days, 14 days. In the 8th day, he sent away the people."
Now, if the people celebrated for 7 days before a holiday that takes place on Tishrei 15, it is evident that Yom Kippur [Tishrei 10] was one of the days of eating and drinking. It is notable that later Israelite-Jewish literature (see B. Moed Qatan 9a,Bershit Rabba 35:4) in fact reads the text this way to say that Yom Kippur was not observed that year although their assumptions about the authorship of Dt force them into assumptions without textual basis. There are, to be sure, those (Radaq, Abarbanel) who try to argue there was no eating or drinking on Yom Kippur. Similarly, the fact that Shlomo dismissed the people on the 8th day, after 7 days of observing the holiday would show that Shmeni Atzerot was not observed. Since we see that the author of Kings assumes Yom Kippur and Shmmini Atzerot were not observed in Jerusalem in the time of Shlomo, it certainly seems likely that the author of Dt. also did not know of these festivals.
But, it will be argued, we have proven too much. For the author of Dt knows of 3 festivals, the author of Kings knows here of only 1 ("the holiday"). This view is supported by a number of citations. For example, Judges 21:19 knows of bur one yearly festival in Shilo (which the Temple in Jerusalem clearly regarded as anscestral to itself), Elqanah, presented as a model of piety, goes to Shilo but once a year (I Samuel 1:3--note the multiplicity of conflicting efforts by standard Jewish commentators to explain this away). When the author of Kings wants to explain why the rival Temple in Beit El [and this is an important reminder that Jerusalem was NOT the only Temple and we do not know what holidays were celebrated in those places] celebrates in the 8th month, the text is (I Kings 12:32) "And Yerovoam made a holiday in the 8th month on the 15th day of the month as the holiday [which one?] that is in Yehuda."
For the author of Kings, there is no problem. For in II Kings 22-23, that author will tell how in the time of the reforming (maybe the wrong adjective ?) 7th century Judean King Yoshiyahu, there will be "found" a book of the Torah that sounds a lot like Dt. And in II Kings 23:21, Yoshiyahu will tell his people to observe a Pesah in accordance with the prescriptions of this book "For there was not done as this Pesach from the days of the judges that judged Israel [over 3 centuries before this]and all the days of the Kings of Israel and the kings of Yehuda." [Yes, I know about the material in Joshua & Esther but it would take another dvar torah to explain why that is not reliable material as too what happened in the Jerusalem Temple].
Until the 7th century, one holiday in Jerusalem. From that point 3 holidays: the 3 we find in Re'eh? It's not that clear. Again, we note that a very different Pesah--that of Exodus 12--exists. Indeed, the Sifrei (Devarim 129:2)spends a lot of its energy trying to reconcile the Pesah of Re'eh with the Pesah of Parshat Bo. In Bo, the exodus is by day, here it is at night. In Bo, sheep and goats are the sacrifice, here it is cattle also. In Bo, the sacrifice is roasted, here it may be cooked. On the other hand, two centuries after Yoshiyahu, the Israelites of Elephantine in Egypt evidently do not have Dt---and they are just being introduced to Pesah (see B. Porton "Papyri From ELephantine"). Similarly, Re'eh has 3 holidays. There is no mention of Shevuot in Kings. The author of the 2nd half of Ezekiel (445:12) knows only of Sukkot and Pesach [but then, that author also knows of a variety of strange rituals--there were reasons why the Rabbis wanted to exclude Ezekiel from the canon. Similarly, III Esdras ( a Greek account parallel to parts of Chromicles, Ezra, and Nehemiah) credit the returning exiles only with observing Pesach and Sukkot.
In any case, what we have not found, anywhere during the period of the 1st Temple, are the other holidays of Tishrei: Rosh HaShanah, Yom Kippur, Shmeni Atzerot/Simhat Torah. We have more luck when we reach the period of the 2nd Temple (Could this be because the returning exiles bring the traditions of other Temples into the Jerusalem establishment?). On the one hand, there is Chronicles, basically a rewritre of Kings. But the author of Kings ends the story in the 6th century BCE and probably lived around that time. The author of Chronicles carries the story (see the list of Davidic descendents in I Chronicles 3) down to the early 4th century so that author could not have written before then. II CHronicles 5-7 reruns Kings 8 with an important change (7:9) " And they made on the 8th day Atzerot for the dedication of the altar they did 7 days (so this author is still not worried about Yom Kippur) and the holiday 7 days. (10) And on the 23rd day (i.e. after Shmeni Atzerot), he sent the people to their tents". So this author knowsw about Shmmini Atzerot but not about Yom Kippur! (Note that the author of Chromicles also introduces changes into the history of Pesach).
The other reference is Nehemiah 8. {Note a connection between the author of Nehemiah and the author of Chronicles is often assumed) Talking about activities in the very late 5th century (around the time of Elephantine, we have an assembly on the 1st day of the 7th month. The day is said (8:10) to be holy. Is this the Yom Zikkaron Taruah of Leviticus 23:23 (the name Rosh HaShanah is of course rabbinic)? Or is it just a Rosh Hodesh? We don't know. But we do know that the author of Nehemiah does not know of Yom Kippur for the repentence of the people on Tishrei 1 leads to a fast...on the 24th of Tishrei (see 9:1ff but see also Bickerman "The Jews in the Greek Age" who tries to argue there was a Yom Kippur but it was not a holiday with which non-Priests were concerned).
But Nehemiah's account of Sukkot contains another detail. The people make sukkot and dwell in them, something that the text says had not happened since the time of Yehoshua (8:14-16 but see B Arkhin 32b and Malbim for atttempts to explain away these verses). At once, we realize that there is no such command in Re'eh. One might object that the focus of Re'eh is on assembling in the central shrine. But in the equivalent case of Pesah (Dt. 16:3) the text does mention the copmmand of eating matzah. Hence, had the author of Dt known of the command of dwelling in a Sukkah, it should be mentioned. Rather, dwelling in a Sukkah, having an 8th day (which is in Nehemiah 8:18), and (possibly) having a holiday on the first day of Tishrei are all ways in which the author of Nehemiah is clearly following Lev. 23 rather than Re'eh.
Yet, all the material in Lev. 23 is still not known to that author. Yom kippur is not the only example. In Nehemiah 8:15, we read that the people were to bring on Sukkot "leaves of olives and leaves of oil trees and leaves of mrytles and leaves of palms and leaves of thick trees to make sukkot". Now, this cannot mean to mean sukkot to live in (see Malbim)for in that case, why these materials. Rather, we are encountering the command of the lulav--a command also unknown in Re'eh--but a lulav without an etrog, quite different from the 4 species that, based on Lev 23 are now used. It is notable that both Yom Kippur and Lulav are introduced in Lev 23 with "Ach" (But) as if these are hurried insertions into a text that is becoming holy and, therfore, beyond change.
We started to look at the hagim. And what looked back at us was some 7 centuries (10c-4c BCE) of change, of different people doing very different things, of holidays being observed at different times. And we have still not met Hanukah or Purim. Our holidays of today do not date from a single time but are the results of a long process. Perhaps the most important lesson for the Yomim Noraim is that to be part of a tradition is not to be a passive recipient but rather to active mold and change that tradition.