5 The Lord is the portion of my possession and my cup9; you make my future secure. 6 It is as if I have been given fertile fields or received a beautiful tract of land. 7 I will praise the Lord who guides me; yes, during the night my kidneys instruct me15. 8 I set the Lord before me continually16; because he is at my right hand, I will not be shaken. 9 So my heart rejoices and I am happy; my life is safe.
Berakhot 61aBabylonian Talmud
Rav said: The evil inclination is like a fly and it sits between the two entrances of the heart, as it is stated: “Dead flies make the ointment of the perfumer fetid and putrid” (Ecclesiastes 10:1). And Shmuel said: The evil inclination is like a type of wheat, as it is stated: “Transgression [ḥatat] couches at the door” (Genesis 4:7); ḥatat is interpreted homiletically as related to ḥitta, wheat. The Sages taught in a baraita: A person has two kidneys; one advises him to do good and one advises him to do evil. And it stands to reason that the one advising him to do good is to his right and the one that advises him to do evil is to his left, as it is written: “A wise man’s understanding is at his right hand, but a fool’s understanding is at his left” (Ecclesiastes 10:2). Tangential to the subject of kidneys, the Gemara cites that which the Sages taught in a baraita with regard to the roles of various organs: The kidneys advise, the heart understands, the tongue shapes the sounds that emerges from the mouth, the mouth completes the shaping of the voice, the esophagus takes in and lets out all kinds of food, the trachea produces the voice,
Notes and References
"... We obviously know that left (Latin sinister, sinistra) has a bad connotation in the Western tradition, although not ubiquitously. The kidneys appear in the above excursus as the informants of the heart. Another biblical source considers that the kidneys give only positive advices. We read [Psalm 16:7-9] ... Again, the kidneys and the heart are mentioned in close relationship. At night, explains Abraham ibn Ezra, the heart is free from any alien business, and the kidneys represent the forces of generation [Hebr. toladah] which are hidden as the kidneys are concealed. The kidneys are the concealed seat of thought and desire. The Lord “tries the reins and the heart”. But He also infuses in the kidneys “Law and wisdom”, as stated in a Midrash trying to explain how our father Abraham had been granted knowledge of the Law ..."
Kottek, Samuel S. My Reins Admonish Me at Night (Psalm 16:7) The Kidneys in Ancient and Medieval Jewish Sources (pp. 465-478) Medicina Nei Secoli Arte e Scienza, 22/1-3, 2010
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