How did Rabbi Judah the Prince's bookcase look like?
As the most distinguished and rich Pharisee of his time, what books besides the Tanach, did he have in his library around 200 CE?
EDIT: As Rambam mentions in the preface to the MT, I understand that Rabbi had numerous handwritten notes from other Tannoyim, but were any of them (of the Oral tradition) compiled and distributed as a finished work?
There were several texts of Oral Law written prior to Mishnah. According to Iggeres Rav Sherira Gaon, (ch. 2) Rebbi mastered 13 approaches to the laws (see also Nedarim 41a).
When Rebbi had mastered 13 approaches to the laws, he taught r. Chiyya 7 of them. Rebbi took ill and forgot them. R. Chiyya restored the 7, but the other 6 were forgotten. There was a launderer who had heard when Rebbe used to recite them. R. Chiyya went and learned them from the launderer. [R. Chiyya] then went and repeated them before Rebbi. When Rebbi used to see the launderer, he would say to him: "You made me and r. Chiyya", According to some, he would say: "You made Chiyya, and Chiyya made me".
Very likely, this gemara alludes in part to the following texts. R. Yishmael and R. Shimon b. Yochai write two midrashei Mechilta, R. Chiya b. Abba wrote Sifra, also big portions of Sifre where written by different authors (described in Iggeres ch. 5). Tosefta of. R. Chiya and r. Oshaya were also studied by Rebbi - R. Yehudah ha Nasi (described in Iggeres ch. 4).
In the view of the discussion, it's good to note, that the production of the Mishnah was a 2-tiered process, as Rambam points in his "Introduction to Mishna". The same idea is developed further in the introduction to the Netziv's commentary Ha’amek Sh’alah to Sheiltos of Rav Hai Gaon (translated as "The Path of Torah"). Netziv notes that development of halachah is a 2-tiered process, which was performed by Sanhedrin. The process consisted of
1-st tier - legislation: issue of psak halacha to various life circumstances
2-nd tier - adjudication: combining of similar laws into a single halacha l'ma'aseh.
One can see an example of such a system not only in halacha but also in the 2nd perek of masechet Pirkei Avot with 5 students of Rabbi Yochanan ben Zakkai. There are 4 students who work hard arriving at an independent psak: Rabbi Eliezer ben Hyrcanus, Rabbi Joshua ben Hananiah, Rabbi Yose haKohein, and Rabbi Shimon ben Nethanel, and then comes the smartest of all Rabbi Eleazar ben Arach and makes the punchline. What is the purpose of the discussion in Avos? It is precisely to explain with simple examples how the 2-tiered process at arriving at halacha worked. R. Eleazar ben Arach did not work as a posek / legislator, he worked as an adjudicator, while the four other rabbis covered all the possibilities with their independent and diverse psak.
Such was development of the Mishnah. As evidence shows, the previous halachic work included mostly halachic commentary on Chumash and other books of Nach, which were available in some form and evidently edited later. Rabbi Yehuda haNassi's job was to produce a singular halachic work, which would unite approaches of other hachamim. He was a great adjudicator, while others produced psak to make the system work.
Mishnah was written in circumstances which radically differed from previous halachic work, when there was the Temple. Netziv explains that the holiness of the Temple somehow allowed to effortlessly arrive at the correct formulation, and no painful process of halachic argumentation was necessary. As a result, towards the end of the Temple, under Roman occupation, hachamim lacked the skill neccessary to make a correct psak. In Netziv's opinion, that's precisely what caused hesitation of R. Zecharia ben Avkulos regarding Bar Kamtza in Gittin 56a.
After the Temple destruction, a diverse legislative work was performed for several generations until a mature body of halacha emerged, and Mishna united these approaches at the end. In fact, many discussions in the gemara one can also view in exactly the same 2-tiered format as actually pointed out by sefer Havot Yair (see Talmud Reclaimed by R. Shmuel Phillips). Ravina and Rav Ashi were adjudicators of Gemara. R. Yosef Caro and R. Moshe Isserlish were adjudicators of Shulchan Aruch, etc.
Sefer "Kerem Yehoshua" by R.Yehoshua Cohen, p.157-159, when discussing arguments between Rashi and Tosafos, writes the following about the sources of R. Yehudah haNassi's learning:
Jerusalem Talmud, Shabbos 10:5 (63b) and Pesachim 10:1(68b) state that any law which R, Yehudah haNassi taught he learned from his mentor R. Yaakov ben Kodeshai (Korshai).
At first glance this seems strange, for in the Babylonian Talmud we find that R. Yehudah haNassi had many teachers:
(Note 7 sources in light with Nedarim 41a!) However, nowhere in the Babylonian Talmud does it mention that he learned from R. Yaakov ben Kodeshai (Korshai)! So how can the Jerusalem Talmud say that any law he taught he must have heard it from R. Yaakov ben Kodeshai (Korshai), and not from any other teacher we listed?
The key to this puzzle can be found in Avodah Zarah 19a, which states in order to learn the logic and reasoning process of the Talmud (סברה) it is best to learn from several teachers, while in order to learn the text itself of the Talmud, as passed down by tradition, it is best to learn from one teacher, so as to avoid contradictions of wording. Likewise we find in Eruvin 53a: the Judeans studied from one rabbi and their Torah stayed with them permanently; the Galileans did not study from one rabbi, and their Torah did not stay with them permanently." Rashi explains (s.v. לא גמרי מחר רבה): "They [the Galileans] heard [the Gemara] from one rabbi i one wording and from another in a different wording. And even though both [rabbis] had the same thing, the change of wording confused them and made them forget."
Based on this we can explain as follows: The Jerusalem Talmud knew that all of R. Yehudah haNassi's teachers, listed above, only taught him logic and reasoning, after he had already learned the traditional text. But his principle rabbi, who taught him the text itself as passed down by tradition, was R. Yaakov ben Kodeshai (Korshai).
Btw. R. Yose b. Halafta wrote Midrash Seder Olam.
