The kidneys in the Bible: what happened?

The kidneys, always used in the plural (kelayot), are mentioned more than 30 times in the Bible. In the Pentateuch, the kidneys are cited 11 times in the detailed instructions given for the sacrificial offering of animals at the altar. Whereas those instructions were for purification ceremonies at the Temple, sacrificial offerings were made subsequently in seeking divine intervention for the relief of medical problems. In the books of the Bible that follow the Pentateuch, mostly in Jeremiah and Psalms, the human kidneys are cited figuratively as the site of temperament, emotions, prudence, vigor, and wisdom. In five instances, they are mentioned as the organs examined by God to judge an individual. They are cited either before or after but always in conjunction with the heart as mirrors of the psyche of the person examined. There is also reference to the kidneys as the site of divine punishment for misdemeanors, committed or perceived, particularly in the book of Job, whose suffering and ailments are legendary. In the first vernacular versions of the Bible in English, the translators elected to use the term "reins" instead of kidneys in differentiating the metaphoric uses of human kidneys from that of their mention as anatomic organs of sacrificial animals burned at the altar. This initial effort at linguistic purity or gentility has progressed further in recent versions of the Bible, in which the reins are now replaced by the soul or the mind. The erosion may have begun in the centuries that followed the writing of the Bible, when recognition of the kidneys as excretory organs deprived them of the ancient aura of mysterious organs hidden deep in the body but accessible to the look of God. At approximately the same time, Greek analytical philosophy argued that the brain, which is never mentioned in the Bible, was the most divine and sacred part of the body. This argument gained ground in the past century, when the functions of the brain were elucidated, and ultimately established in the 1960s, when salvaging the kidneys for transplantation necessitated a change in the definition of death as irreversible brain function. It is ironic that advances in understanding kidney function and in nephrology that made kidney transplantation feasible may have contributed, albeit indirectly, to the gradual elimination of the metaphoric mention of human kidneys in the Bible.