The principle that the tongue touches the upper palate is that "the mouth is closed, and the tip of the tongue and the front part of the tongue naturally stick to the upper gum", which is usually correct. "The tongue touches the upper gum with the bottom of the tongue" is misunderstood by many practitioners as "the tongue is rolled up". To illustrate the correctness of the above practice, we must first clarify the function of "tongue against palate". The function of "tongue reaching the palate" is: first, it produces fluid, and second, it opens the channels of Ren and Du. The tongue naturally sticks to the palate, how to naturally stick to the crotch? The artistic conception is that the mouth has a tongue, the son has a tongue, and the son has a long stream of fluid. Let's have a try. Hold your tongue naturally and let the upper jaw touch it, no matter where it touches the surface of your tongue. With your tongue in your mouth, you can speak freely in a short time. If the tongue rolls to the upper jaw, not only will the mouth be stiff, but the face and the whole head will be tense and dry.
In practice, it is generally unnecessary to deliberately "put your tongue on the palate". If you feel uncomfortable on the tongue palate, which will affect your practice, you don't need to ask this part to be in place. When it is necessary to take over the Du meridian after dredging it, there will naturally be magnetic attraction to make the tongue stick to the upper jaw and penetrate the Ren meridian.
Taoist practitioners say that the tip of the tongue should be placed where the "shua" sound is pronounced.