The Heavenly Worthy said to Perfected Zuoxuan: Whoever wishes to cultivate the Tao must first be able to renounce affairs. When outer affairs are all cut off and nothing troubles the mind, then sit at peace and observe inwardly as thoughts arise. If you notice a single thought arising, you must extinguish it and make the mind peaceful. Next, even if there is no definite greed or attachment, drifting and confused thoughts must also be completely extinguished. Practice diligently day and night, never slackening for a moment. Extinguish only the moving mind, not the illuminating mind. Concentrate only the empty mind, not the abiding mind. Rely on no single method, and the mind will constantly abide. Yet the ordinary mind is restless and competitive. For a beginner, stilling the mind is very difficult; sometimes it cannot be stilled, or it stops briefly and then is lost again. Going and staying do battle, and it flows through the hundred parts of the body. Only after long and refined concentration does it become well tamed. Do not, because you cannot gather it in for a while, abandon the work of a thousand lifetimes. Once you have gained a little stillness, then in walking, standing, sitting, and lying down, in the midst of affairs, and in noisy places, always set your intention on peace. Whether there are affairs or not, be always as if without mind. Whether in stillness or in noise, keep your will single. If you bind the mind too tightly, it will become an illness; qi erupting in madness is its sign. If the mind does not move, you must also let it go free. When tension and ease are properly balanced, it will always be well regulated. Restrain it without clinging; release it without letting it move. To be in noise without aversion and to engage in affairs without vexation—this is true concentration. Do not, because you engage in affairs without vexation, seek out many affairs; do not, because you are in noise without aversion, force yourself into noise. Take being without affairs as your true dwelling and having affairs as responding traces. Like a mirror of water that reflects, it shows forms according to things. Skillful means can only bring one into concentration; whether wisdom arises slowly or quickly does not depend on the person. Do not, in concentration, hastily seek wisdom. Haste harms one's nature; harmed, there is no wisdom. If in concentration one does not seek wisdom and yet wisdom arises of itself, this is called true wisdom. Having wisdom yet not using it, true knowing seems like foolishness. This increasingly nourishes concentration and wisdom, both beautiful without limit. If in concentration thoughts arise, one will attract many evils; demonic sprites and the hundred goblins appear in response to the mind. If what one sees are the Heavenly Worthies and the immortals and Perfected, these are auspicious signs. Only let there be, above the settled mind, vast openness with nothing covering it, and below the settled mind, vast spaciousness with no foundation. Old karma dissolves day by day, and no new karma is made. With nothing to hinder or obstruct, one breaks far free of the cage of dust. Practice this for long, and attaining the Tao comes as what is so of itself.
A person who attains the Tao has seven signs in all. First, the mind easily attains concentration and perceives all the outflows of dust. Second, old illnesses all disappear and body and mind are light and refreshed. Third, what was depleted by early decline is replenished, youth is restored and life renewed. Fourth, one's lifespan is extended by several thousand years; this is called an immortal. Fifth, one refines the body into qi; this is called a Perfected. Sixth, one refines qi into spirit; this is called a divine person. Seventh, one refines spirit to merge with the Tao; this is called a supreme person. The power of their insight grows brighter with each sign. When the supreme Tao is attained, wisdom is fully complete. If one has studied settling the mind for a long time without a single sign in the body—a shortened life and defiled substance, the complexion fading and then only emptiness—and yet calls oneself awakened in wisdom and claims to have attained the Tao, this is truly not the principle of seeking the Tao. A hymn says: Knowing arises from objects; fire arises from conditions. Each is the true moving nature; following the flow, one loses the source of the Tao. Raising the mind to still knowing, the mind arises and knowing grows more troubled. Understanding that nature is originally empty, knowing is then the gate of all wonders.
(From the Commentary on the Dongxuan Lingbao Scripture on Concentration and Observation. The author is not originally recorded; the scripture dates roughly from the end of the Northern and Southern Dynasties or the Sui–Tang period. It describes the Taoist practice of stilling the mind and settled observation and then lists the signs of the different stages in cultivating the Tao, offering strong guidance for spiritual practice.)