The number 30 appears thrice, as it happens, in a brief Talmudic discussion of the Rabbi Eliezer’s teaching style:
Our Rabbis have taught: It happened that R. Eliezer passed the Sabbath in Upper Galilee, and they asked him for thirty decisions in the laws of Sukkah. Of twelve of these he said, ‘I heard them [from my teachers]’; of eighteen he said, ‘I have not heard’…. They said to him, ‘Are all your words only reproductions of what you have heard?’ He answered them, ‘You wished to force me to say something which I have not heard from my teachers. During all my life [I may tell you] no man was earlier than myself in the college, I never slept or dozed in the college, nor did I ever leave a person in the college when I went out, nor did I ever utter profane speech, nor have I ever in my life said a thing which I did not hear from my teachers.’
— Babylonian Talmud, Sukkah 28a
The passage goes on to describe a similar set of habits ascribed to Eliezer’s teacher, R. Johanan ben Zakkai, concluding: “…so did his disciple R. Eliezer.” This is followed by more background on Eliezer’s teacher:
Our Rabbis have taught: Hillel the Elder had eighty disciples, thirty of whom were worthy of the Divine Spirit resting upon them, as [it did upon] Moses our Master, thirty of whom were worthy that the sun should stand still for them [as it did for] Joshua the son of Nun [cf. Josh. 10:12ff], and twenty were ordinary. The greatest of them was Jonathan b. Uzziel, the smallest of them was Johanan b. Zakkai. They said of R. Johanan b. Zakkai… [see below]… And if the smallest of them was so great, how much more so was the greatest?
“They said of R. Johanan ben Zakkai” that he did not neglect the following areas of study:
- Mishnah [teachings of the Rabbis],
- Gemara [explanations of mishnah],
- Halakhah [decisions of law],
- Aggada [homilies, legends, etc],
- details of the Torah,
- details of the Scribes,
- inferences a minori ad majus,*
- calendrical computations,
- gematrias [teachings based on numerical equivalents of words],
- the speech of the Ministering Angels,
- the speech of spirits,
- the speech of palm-trees,**
- fullers’ parables***
- and fox fables.****
This eclectic list includes additional mystical and exegetical areas (a very similar list appears in Baba Bathra 134a.)
It is interesting to compare Rabbi Eliezer’s extreme conservatism — refusing to teach anything not received directly from his teacher — with the description of his teacher’s varied background. In particular, several forms of exegesis are within R. Johanan’s expertise, while R. Eliezer refuses to engage in his own decision-making, in the passage above and elsewhere in the Talmud.
It’s noteworthy, too, that “Our Rabbis” are recalling these teachers, presumably from some distance. Rabbi Louis Jacobs suggests that generations after R. Eliezer viewed him with some suspicion, noting Eliezer’s famous excommunication as a result of his failure to abide by majority decision.
See also: The essay on Wikipedia about Talmudic Hermeneutics and this additional note on R. Eliezer.