Excerpt from the Dhyāna Samādhi Sūtra

Furthermore, contemplate the body as empty space. Constantly practice this contemplation. The power of aspiration, the power of diligence, the power of single-mindedness, and the power of wisdom become extremely vast. Then one can lift the body, gradually leaving the seat and ascending into the void. Just as a powerful wind can carry heavy objects far away, lifting the body is also like this. Initially, one should test oneself, lifting off the ground by one foot, two feet, gradually reaching ten feet, then returning to the original place. It is like a fledgling bird learning to fly, or a child learning to walk. Continuously reflect, examine, and assess one's own mental power. In time, knowing that one's mental power has grown great, one will certainly be able to fly far.

Further, practice contemplating the Four Great Elements within oneself. Remove the perception of the earth element, contemplating only the water, fire, and wind elements. Keep the mind focused and undistracted. Afterwards, the body will attain freedom, without any obstruction, like a bird in flight. At this point, one should further practice contemplation, perceiving the distant as near. By eliminating the perception of spatial distance, the body can instantly reach distant places as if they were nearby.

Why does perceiving the distant as near and eliminating the perception of spatial distance allow the body to instantly reach distant places as if they were nearby? This is because such perception causes the manas (mind root) to believe it. When the manas truly believes it and holds this view, the tathāgatagarbha (Buddha-nature) will necessarily conform to the manas and manifest such a state. Spiritual powers function this way; all phenomena are like this. Whatever the manas believes will appear. Transforming the manas can transform everything. Therefore, true self-confidence is the faith of the manas. As long as the manas believes, nothing is impossible to accomplish. Attaining Buddhahood operates on this very principle. How immense, then, is the power of selflessness when the manas realizes selflessness and believes in it? It severs self-attachment and all afflictions, extinguishes all notions of self, liberates the mind, and enters the quiescent nirvana.