Excerpts from the Sutra on Sitting in Meditative Absorption (Zuochan Sanmei Jing)

Original text: 复次观身空界。常习此观。欲力精进力。一心力慧力。极为广大。便能举身。如大风力。致重达远。此亦如是。初当自试。离地一尺二尺。渐至一丈。还来本处。如鸟子学飞。小儿学行。思惟自审。知心力大。必能至远。学观四大。除却地大。但观三大。心念不散。便得自在。身无挂碍。如鸟飞行。当复学习。远作近想。是故近灭远出。

Explanation: Furthermore, contemplate the space element of the physical body, regarding the body as empty. Practice this contemplation constantly, and the power of aspiration will grow ever more vast; the power of diligence, the power of one-pointed concentration, and the power of contemplative wisdom will become extremely vast. At that point, one can lift the body up—the body gradually leaves its seat and rises into the sky. It is as if a very powerful wind carries a heavy object far away; lifting the body works the same way. At the beginning, one should test oneself little by little: let the body leave the ground by one or two feet, gradually up to a full zhang, and then return to the original place. It is like a fledgling bird learning to fly, or a small child learning to walk. Through constant deliberation and self-examination of one's mental power, at a certain point one knows that one's mental power has become very great, and that one can certainly fly to distant places.

Then cultivate and contemplate the four great elements of one's own body—earth, water, fire, and wind. Remove the earth element from the mind and contemplate only the three elements of water, fire, and wind, keeping the mind single-pointed and undispersed. Afterward, the body will attain mastery, free of any obstruction, flying like a bird. At this point, one should further learn to contemplate by regarding the distant as near, extinguishing the notion of spatial distance, so that the body can instantly reach a distant place as if it were nearby.

Why is it that by regarding the distant as near and extinguishing the notion of spatial distance, the body can instantly reach a distant place as if it were nearby? Because by thinking in this way, the manas is made to believe it. Once the manas truly believes it and holds it to be so, the tathāgatagarbha will necessarily accord with the manas and transform and construct such a realm. Supernatural powers work this way, and all dharmas work this way: whatever the manas believes will manifest. Changing the manas can change everything. Therefore, true self-confidence is the faith of the manas—as long as the manas believes, nothing cannot be accomplished; attaining buddhahood works on precisely this principle. Then, if the manas realizes no-self and believes in no-self, how immense would the power of that no-self be? One would eliminate self-grasping and all afflictions, extinguish all notions of self, the mind would attain liberation, and one would enter tranquil nirvāṇa.