Rabbi Yohanan and Rabbi Simeon ben Laqish were among the most distinguished Jewish scholars of the third century, and in keeping with the argumentative spirit of Talmudic discourse, their relationship was often characterized by animated controversies and debates.

Rabbi Simeon, who had been a gladiator prior to turning his energies to Torah scholarship, had a tendency to run afoul of the authorities. He was particularly outspoken when it came to criticizing the Patriarch (Nasi), who held the highest administrative position in the Jewish community.

On one occasion (Yerushalmi Sanhedrin 2:19d–20a), Rabbi Simeon’s anti-authoritarian diatribes succeeded in offending the Patriarch to such a degree that the latter dispatched a troop of mercenaries to arrest him. Rabbi Simeon escaped and went into hiding.

Shortly afterward, the Patriarch decided to pay a visit to Rabbi Yohanan’s academy in Tiberias. The visitor soon noticed that his host did not seem interested in lecturing, and eventually he prodded the rabbi to commence expounding words of Torah.

Rabbi Yohanan started clapping with one hand. When the Patriarch expressed his bewilderment at Rabbi Yohanan’s strange and ineffectual behaviour, he had in fact been set up for the delivery of the punch-line:

To attempt to study Torah without his usual study partner, said Rabbi Yohanan, was as unproductive an enterprise as trying to clap with one hand.

The Patriarch conceded the point and agreed to give the delinquent Rabbi Simeon another chance.

I recently had occasion to quote the above story when called upon to say farewell to a valued university colleague who had decided to give up his academic career and join a Buddhist monastery. Rabbi Yohanan’s metaphor conveyed aptly how much I had been enriched over the years through my continuing exchanges and debates with my colleague, and how the intellectual atmosphere of our department would suffer from his absence.

Of course, my choice of this particular Talmudic anecdote was also influenced by its use of the distinctive imagery of “one hand clapping.” That enigmatic expression is arguably the Buddhist teaching that is most widely known among non-Buddhists.

The question “What is the sound of one hand clapping?” is a quintessential example of a “koan,” a brief meditational saying by means of which Zen Buddhist masters test the enlightenment of their students and of each other. Koans often try to express spiritual intuition by making use of non-rational, paradoxical language, as a way of pointing to a reality that transcends logical discourse.

The “one hand clapping” koan is ascribed to Hakuin Ekaku (1686–1769), one of the most celebrated masters of Zen Buddhism in Japan. Hakuin is credited with bringing about a renaissance in Japanese Buddhism after three hundred years of decline. As a teacher, he placed special emphasis on the study of koans, as a most effective path to spiritual enlightenment.

Apart from my chauvinistic interest in pointing out that the Jewish use of the paradox predated the better-known Buddhist one by fifteen hundred years, I believe that it is particularly instructive to observe how a single metaphor can be put to such extremely diverse uses.

However, we must be careful not to interpret these differences as constituting an essential contrast between the supposed otherworldliness of Buddhism and the scholarly dialectics of Judaism.

The truth is that both these religious traditions can boast of rich and variegated heritages that have accommodated broad ranges of spiritual expression, including ecstatic visionaries, worldly pragmatism, and exacting rationalism. Some Buddhist monasteries encourage intense debate over fine points of logic, reminiscent of the arguments of yeshivah students. Conversely, Jewish mystics have resorted to paradox and symbolism in order to point to spiritual realities that cannot be encompassed by conventional language.

It is intriguing to speculate whether the remarkable metaphor of one hand clapping wandered along some inscrutable route from third-century Israel to eighteenth-century Japan, or if there was an earlier, lost source, from which both traditions drew. Although it is impossible to determine such questions with any degree of certainty, it seems most likely that Rabbi Yohanan and Hakuin fabricated their respective expressions, er, single-handedly.

The ingenuity of both sages deserves our admiration. Perhaps this would be most effectively expressed in the form of prolonged rounds of mute applause.