Musar su Salmi 42:8

And just as He made the pillars of the earth below the earth, so has He made as the foundation of the structures of the body, the bones of the pelvis on this side and that, and the two thighs. And just as He made stones which are firmly set in the depths and from between which the water goes forth, so did He make the two kidneys so that from between them and from their sinews the water of the legs, that is to say the urine, goes out to the urinary tract; and also the semen crosses and goes forth from between them to the testicles. And just as deep calls unto deep, as it is written, "Deep calleth unto deep" (Ps. 42:8), so does the upper bowel, which is the stomach, call to the intestines to receive the rest of the food and the drink. And the bowels call to the sinews of the kidneys, which are like tubes, to receive the water. The urine is pressed out and separated from the food in the intestines to go to the urinary tract. And the tubes of the kidneys call out to the sinew of the urinary tract to receive those waters, to cause them to be gathered within the bladder which may be compared to the lowest depth, for it is the lowest of all the bodily depths. Moreover, that intestine calls to the intestines leading from the stomach to receive the excrement.