The main purpose that the Stomach and the Spleen serve together is to purify the food that we eat and then transport it to the Lungs to then be spread to the rest of the body. The stomach is the receptor of the food, then the spleen is responsible for separating the usable parts of food from the unusable. The stomach and spleen are yin and yang to each other, and one way in which they balance each other out is by sending Qi in opposite directions. The spleen sends it upwards and the stomach pulls it downward.