A bat kol, literally “daughter of a voice,” refers to a heavenly voice that proclaims God’s will or a divine judgment in a matter of legal dispute. The term itself doesn’t appear anywhere in the Hebrew Bible, though God’s voice is heard frequently in the Bible. Later sources indicate that there were bat kols in biblical times that were not recorded in the text, as in the Talmud’s declaration that a bat kol announced the death of Moses.
The clearest statement of the nature of the bat kol is the Talmud’s declaration that the bat kol served as a means of communication between God and humankind after the end of the prophetic era. Though this teaching clearly connects a bat kol to the prophecies of the Bible, instances of the latter indicate explicitly in the text that it is God speaking, while the language of “daughter of a voice” concerning a bat kol suggests it is some sense a lesser (yet still divinely originating) voice. The Tosafot, commenting on a passage concerning a bat kol in Tractate Sanhedrin, distinguishes it from a voice that descends directly from heaven (which might refer to traditional prophecy), comparing it instead to an echo, a voice that emerges from within another voice.
The term appears only twice in the Mishnah, but it is found frequently in the Talmud, perhaps most famously in the story of the oven of akhnai. In this story, which appears in the Talmud in Tractate Bava Metzia, the rabbis are discussing the purity status of an earthenware oven that has been cut into segments with sand placed in between each segment. Rabbi Eliezer deems such an oven ritually pure, but the majority of his colleagues disagree, and when he can’t persuade them he resorts to a bit of magic, causing a tree to uproot itself, a stream to flow backwards, and the walls of the study hall to nearly collapse. But none of this persuades the other rabbis.
Finally, he declares that heaven will prove him right. Sure enough, a bat kol descends from heaven and declares that the law should follow Rabbi Eilezer’s opinion. At which point, Rabbi Yehoshua leaps to his feet and, quoting a verse from Deuteronomy, states: “It is not in heaven.” The implication being that the Torah has already been given and it is up to human beings, not God, to decide how it’s interpreted.
The other famous story of a bat kol in the Talmud suggests a very different principle. In Tractate Eruvin, we find this teaching:
For three years Beit Shammai and Beit Hillel disagreed. These said: The halakhah is in accordance with our opinion, and these said: The halakhah is in accordance with our opinion. Ultimately, a bat kol emerged and proclaimed: Both these and those are the words of the living God. However, the halakhah is in accordance with the opinion of Beit Hillel.
In this story, the determination of the divine voice is heeded, as indeed in most matters Jewish law does follow the opinion of Beit Hillel, even though both Hillel and Shammi are teaching the word of God. The Talmud’s famous statement eilu v’eilu divrei elohim chayim — these and those are the words of the living God — is widely cited as evidence of Jewish tradition’s validation of multiple interpretations even if in the end one must emerge as the one followed for practical purposes.
It’s unclear why these two stories suggest very different implications of a bat kol. But in the majority of instances in which a bat kol is heard, it is considered authoritative, though in many cases the voice has nothing to do with disputes around Jewish law.
Sometimes a bat kol is heard merely to share information, as in the account of the Ten Martyrs, the rabbinic leaders killed by the Romans following the destruction of the Second Temple, where a bat kol announces that Rabbi Akiva and Rabbi Haninah ben Teradion were granted a place in the World to Come. A similar story in the Talmud concerns a Roman officer who gave up his life to save Rabban Gamliel, after which a bat kol declared that the officer too had been granted a portion in the World to Come. In other instances, the bat kol is a voice of admonition. Tractate Megillah states that when the writings of the prophets were translated into Aramaic, a bat kol asked: “Who is this who revealed my secrets to humanity?” And when Yonatan ben Uzziel identified himself as the translator, a bat kol rang out again to tell him not to translate the Writings.
Sayings like this are found throughout the Talmud. In several places, the rabbis even opine on the nature of the bat kol itself. In Tractate Sotah, it says that the bat kol can speak in multiple languages, evidently to ensure its message is understood by those who need to understand it. And Tractate Megillah states that the bat kol can sound like either a man or a woman depending on where the voice is heard.
Pronounced: TALL-mud, Origin: Hebrew, the set of teachings and commentaries on the Torah that form the basis for Jewish law. Comprised of the Mishnah and the Gemara, it contains the opinions of thousands of rabbis from different periods in Jewish history.
Pronunced: TORE-uh, Origin: Hebrew, the Five Books of Moses.