The kidneys are vital organs that essentially act as the body's filtration system, ensuring that toxins are removed from the blood. They are thus responsible for filtering waste products and other excess substances from the blood, which are then expelled in urine. Additionally, the kidneys play a crucial role in maintaining a balance of electrolytes, regulating blood pressure, and controlling red blood cell production through the secretion of hormones, thus making them crucial overall health and function of both man and animal. One of the oft-repeated instructions for ritual sacrifices given in the Book of Leviticus is that the kilayot (“kidneys”) of an animal sacrifice must be burnt on the altar along with various fats from the animal’s body. In fact, of the thirty-one times that the word kilayot appears in the entire Bible, fifteen of those instances refer to this specific rule (Lev. 3:4, 3:10, 2:15, 4:9, 4:7, 8:16, 8:25, 9:10, 9:19). In the essay before you, we explore the etymology of the word kilayot, and compare it to its two possible synonyms in Biblical Hebrew — atzeh and tuchot.
In addition to the word kilayot in the Bible referring to “kidneys” in the anatomical sense, the word is also used in a more abstract sense to refer to one’s innermost thoughts and motives. It is in this cognitive sense that Hashem is said to have the ability to examine man’s heart and kidneys (Jer. 11:20, 17:10, 20:12, Ps. 7:10). In such contexts, the term kilayot is often translated into English as “reins” (which is related to the English words renal and adrenaline).
Besides for the aforementioned instances of kilayot in the Bible, this word also appears in the Mishnah (Chullin 3:2, 4:1, Tamid 4:3). Interestingly, the word kilayot always appears in the Bible and Mishnah in plural form, although theoretically, its singular form should be kilyah. In the Talmud, the Hebrew/Aramaic word kulya refers to “a single kidney” (Pesachim 64b, Chullin 93a, 97a, 126b, 128b–129a, Bechorot 39a, Kritot 14a, 23a).
Rabbi Moshe Tedeschi Ashkenazi (1821–1898) in his work Otzar Nirdafim (§344) connects the word kilayot to the word kele (“jail, incarceration”), spelled with a final ALEPH. He accounts for this connection by explaining that as internal organs, the kidneys are embedded deep within a person’s body, as though they are “hidden” or “jailed’ inside. Indeed, Ibn Ezra (to Ps. 7:10) understands that the term kilayot can sometimes be meant metaphorically as a reference to the thoughts and beliefs “hidden” deep within a person’s consciousness.
In a similar vein, Ibn Ezra (to Ex. 23:25, Lev. 3:4 and Ps. 16:7, 139:13, cited by Radak in Sefer HaShorashim) connects these two meanings of the word kilayot by postulating that the bodily kidneys are the seat of libidinous desire, leading him to explain kilayot as cognate with the verbs derived from the root KAF-LAMMED-(HEY) that refer to “desiring/longing” in the Bible (II Sam. 13:39, Ps. 119:3, 119:81). A similar point is made by Rabbi Samson Raphael Hirsch (to Ex. 23:18 and Lev. 3:4), who writes that the kidneys are the most profound source of sensuous desire, making them the organs of the evil inclinations and impulses. In line with this, Nachmanides (to Lev. 1:9) writes that burning the kidneys on the altar is so central to the sacrificial rites needed to achieve atonement squarely because the kidneys are instruments of the sort of desire that cause sin in the first place.
In one particular passage, the Bible stipulates that with animal sacrifices, one should remove the fat from opposite the atzeh (Lev. 3:9). This word atzeh only appears once in the Bible, thus making it a hapax legomenon. Yet, Rashi (to Ex. 29:22, Lev. 3:9) and Rashbam (to Lev. 3:9) explain that atzeh means the same thing as kilayot. From where does Rashi’s explanation come?
The Talmud (Brachot 61a) teaches that the two kidneys provide eitzah ("advice") to the heart, with one kidney advising a person to perform good and the other, to perform evil. The Talmud (there) further posits (based on Ecc. 10:2) that the kidney on the right advises for the better, while the kidney on the left advises for the worse. When citing this tradition, Rabbi Elazar Rokeach of Worms (late 12th century Asheknazic scholar) in Sodi Razi adds that the kidneys are also the source of happiness, as it says “and my kidneys shall rejoice” (Prov. 23:16).
Based on the Talmudic tradition, the Talmud (Chullin 11a) explains that the aforementioned Biblical term atzeh refers to none other than the "kidneys," which are the anatomical body part that are said to provide eitzah. This explication of the word atzeh — which clearly serves as the basis for Rashi’s understanding of azteh as synonymous with kilayot — seems to be based on spelling of atzeh as AYIN-TZADI-HEY, which can also be read as eitzah.
For more about these Hebrew words for “kidneys” and other possible related words, please visit us online for the full version of this informative essay: http://ohr.edu/this_week/whats_in_a_word/
