From Rabbi Aryeh Kaplan, “Meditation and the Kabbalah” (Jason Aronson or Samuel Weiser editions), p. 22.
Rabbi Jonathan ben Uziel
Talmud: Sukkah 28a; Bava Batra 134a.
Hillel had eighty disciples.... The greatest was Rabbi Jonathan ben Uziel, while the least was Rabbi Yochanan ben Zakkai.
It is said of Rabbi Yochanan ben Zakkai that he was not ignorant of anything. [He knew] Mishnah, Talmud, law, exposition, grammatical analysis of the Torah, analysis of the Scribes, logical inference, similar wordings, astronomical calculations, gematriot (numerology), incantations for angels, incantations for demons, incantations to palm trees, proverbs of washwomen, proverbs of foxes, a "Great Thing," and a "Small Thing."
A "Great Thing" is the Workings of the Merkava [i.e., the mystical experience], while a "Small Thing" is the discourses [in Talmudic law] of Abaya and Rava....
Since this was true of the least of them, it was certainly true of the greatest. It is said that when Rabbi Jonathan ben Uziel was sitting and studying Torah, any bird that flew by was immediately consumed.