Welcome to Daily Bitachon . We are in our Shaar Habechina series, discussing our digestive system. The Chovot Halevavot provides a beautiful Mashal capturing four forces that operate in our digestive process. Force number one he calls Koach HaMoshech , the "Attracting Force." This draws things into the stomach, much like a central vacuum system in a house where you plug a hose in and it sucks everything in. But once it is sucked in, the next force you have is Koach HaMachzik , the "Holding Force." This holds the food until the body does what it needs to do. Because of this holding, a person does not simply regurgitate; the food is kept in the stomach. We see the importance of this when, lo aleinu , we encounter people who do not have this ability. Then there is Koach HaMevashel , the "Cooking Force," which actually separates the good from the bad and sends the nutrients to the rest of the body. Finally, there is Koach HaDocheh , the "Rejecting Force," which causes the unnecessary waste to leave the body. Rabbeinu Bachya compares this to a king who appointed different servants with designated jobs: The first servant brings the necessary material into the king's treasure house. The second servant properly places it in the storage areas. The third servant prepares and distributes it to meet everyone's needs. The fourth servant cleans everything up when the work is finished. We have all those forces inside of us. We've already spoken about the "Delivery Man," the Koach HaMoshech , which refers to our esophagus. Now let's talk about the "Warehouse Guard," the Koach HaMachzik . This refers to the sphincters and gastric accommodation. If food just passed through the stomach as quickly as it goes through the esophagus, we'd never extract any nutrients. Hashem created "gates"—the sphincters at the top and bottom of the stomach—that lock shut. The stomach also has the specialized ability to relax and expand to hold a large meal without increasing pressure too much. This guard keeps the food in the "furnace" of acid long enough to be broken down. Next is the "Master Chef and Refiner," the Koach HaMevashel . This force "cooks" the food, extracts the pure essence, and separates it from the waste. This is the stage of chemical digestion and small intestine absorption—the most complex part of the "palace." In the stomach, hydrochloric acid and enzymes perform a chemical cook, turning solid food into a liquid called chyme . Once in the small intestine, the Master Chef uses bile from the liver and enzymes from the pancreas to break down molecules to their smallest forms. Then we have the distribution: the walls of the small intestine are lined with millions of tiny, finger-like projections called villi . These are the distribution agents. They pick up the microscopic nutrients—the pure essence—and pass them directly into the bloodstream to be sent to every cell in your body. Following this is the "Janitor," the Koach HaDocheh , which pushes out the leftover waste. This involves the large intestine (the colon) and elimination. After the small intestine has taken every vitamin and protein it can find, "trash" is left over—fiber, dead cells, and bacteria. The large intestine performs one last check, absorbing water to keep you hydrated. Interestingly, the large intestine does not take out all the water, which is why we usually have an easy time. However, if a person is dehydrated, the large intestine "decides" that the rest of the body needs that water more than the waste does. It sucks out all the liquid, and that is when a person becomes constipated. This balance is decided by the large intestine. Finally, through a powerful wave of contraction, this force clears the palace so the waste doesn't rot or cause toxicity. While the Chovot Halevavot does not directly name the kidneys here, he does talk about the "extract of the blood" that goes to the bladder. While the colon deals with solid trash, the kidneys deal with the liquid waste in the blood. The kidney is not just a sponge; it is a collection of about one million microscopic filtering units called nephrons (which is why a kidney doctor is a "nephrologist"). The blood passes through the kidneys like a sieve. Once the liquid is strained out, the kidney looks at the sugar, salt, and vitamins and says, "We need that back!" Your kidneys filter about 180 liters of fluid every single day. If you let all that out, you'd be dehydrated in minutes. Instead, the kidney reabsorbs 99% of it, leaving only about 1.5 liters of concentrated waste, which we call urine. As an aside, the kidney also manages your potassium level—a life-or-death task. If potassium levels get too high, the heart's electrical system shorts out and stops. Every second, your kidneys are measuring and dumping exactly enough potassium to keep your heart beating at a steady rhythm. This is just a touch of what goes on in our refining process through these four servants: the Delivery Man ( Koach HaMoshech ), the Warehouse Guard ( Koach HaMachzik ), the Master Chef ( Koach HaMevashel ), and the Janitor ( Koach HaDocheh ).