A well-structured dome can produce some interesting effects. It can also help explain some obscure passages in the Bible and Midrash.

Allow me to explain these remarks by referring back to wise old King Solomon, to whom Jewish tradition ascribes the biblical book of Ecclesiastes. It is in that book that we find this valuable bit of advice (10:20): “Curse not the king, no not in thy thought; and curse not the rich in thy bedchamber: for a bird of the air shall carry the voice, and that which hath wings shall tell the matter.”

Commenting on this text, the third-century Palestinian sage Rabbi Levi observed: “The walls have ears” (Leviticus Rabbah 32:2).

Rabbi Levi, who lived during some of the more tempestuous days of the Roman Empire, was surely familiar with the role that slanderers and informers played in those perilous games of palace intrigue and backstabbing. Many upright citizens came to unpleasant ends because their unguarded comments were reported to the authorities by unscrupulous deletores.

Unfortunately, this is a state of affairs that persists in many different geographic and historical contexts. The rabbis invoked the precedent of the patriarch Jacob in Genesis 31:4, who invited his wives to the field in order to hold a confidential discussion about what measures to take against the growing hostility of his father-in-law. When Rabbi Akiva spoke admiringly of the Medians for their discretion in taking counsel out in the fields (Berakhot 8b), Rashi explained that “this accords with the popular aphorism that ‘the walls have ears.’”

Variations on this proverb recur in the literatures of many peoples, including works by Chaucer, Cervantes, and Tennyson; though as far as I am aware, Rabbi Levi’s quote in the Midrash is the earliest documented occurrence.

Now, the image of walls with ears is surely a wonderful metaphor for the point it wishes to put across. Nevertheless, there were some literal-minded scholars who were apparently not particularly pleased by the rabbis’ use of such hyperbole.

Such an individual was Rabbi Isaac Lampronti, the eighteenth-century author of the Talmudic Encyclopedia Pahad Yitshak. Lampronti, who lived in Ferrara, Italy, was a striking exemplar of the unique style of Italian Jewish scholarship in all its eclecticism and erudition. More than any other medieval community, the Italian Jews were deeply immersed in the surrounding civilization and succeeded in integrating it with their religious studies. Lampronti’s immense magnum opus, most of which did not see print until centuries after its author’s demise, displays a vibrant intellectual curiosity that embraces all aspects of literature and science from a deeply Jewish perspective.

The Pahad Yitshak contains an entry for “the walls have ears.” As is to be expected, he commences by citing the appropriate sources from the Midrash. But immediately thereafter, he seems to launch into a topic that is totally unrelated, taking his reader on an architectural tour of Mantua.

He proceeds to describe the royal Palazzo del Tè, situated outside the city gates, and focuses on the palace’s large vaulted hall. (Notably, he does not say anything about what lesser figures would have regarded as the palace’s principal attraction, its elaborate erotic frescoes on the theme “the loves of the gods.”)

Rabbi Lampronti is chiefly concerned with the following piece of structural information:

If a person sits in one corner and speaks directly to that corner in a very, very faint voice, so that even those people nearest to him are unable to hear a thing – a person who is listening from the corner at the diagonally opposite angle of the hall will hear whatever he is whispering, clearly and distinctly.

I, the author, have often been there and tested this out and was able to hear, and the truth of the claim will be confirmed by all the residents of Mantua. I have heard that similar structures may be found in many other places in Italy and abroad. This phenomenon is easily understood by anyone who has some familiarity with engineering.

Perhaps this is what our rabbis had in mind when they said that “the walls have ears”; namely, that there are times when a person says something thinking that he has not been overheard. However, he is mistaken, since his words can be heard far away by an ear that is close to the wall, just as if the wall possessed ears to hear with.

Rabbi Lampronti has hereby succeeded in providing a scientifically acceptable explanation for Rabbi Levi’s quip about walls bearing ears: that under proper acoustical conditions, an imprudent whisper from the back row might be embarrassingly overheard by a newspaper reporter at the other extreme of the hall.

The learned rabbi proceeds to apply his interpretation to other Talmudic passages, including the one that warns the potential sinner that transgressions committed in the privacy of one’s home will eventually come to light because “the very stones and beams of a person’s house will testify against him,” as it says (Habakkuk 2:11): “For the stone shall cry out of the wall, and the beam out of the timber shall answer it.” For Lampronti, this is no mere poetic image, but a literal fact of architectural acoustics.

In support of his interpretation, our author cites some unconventional sources, including several that would make our contemporary rabbis cringe, such as Il Cristiano Instruito (“The Well-Educated Christian”) by the monk Paulo Segnori, which describes an insidious vaulted prison whose warden could eavesdrop on the private conversations of all the inmates through a tiny hole in its top.

When all is said and done, there is an eminently practical lesson to be derived from all this: Even when sitting in the last row of the synagogue sanctuary, be exceedingly careful what you say about the cantor. As it teaches in Pirkei Avot (2:4), “Do not utter anything that should not be heard, because in the end it will be heard.”

And besides, the walls have very sensitive ears.