Mr. Zongxuan's Xuan Gang Lun: Chapter 24 on Void Condensation and Quiet Rest

   Awakening aligns with Yang, while sleep merges with Yin. Frequent awakening strengthens the Hun (ethereal soul), and prolonged sleep strengthens the Po (corporeal soul). Those with strong Hun belong to the path of life; those with strong Po belong to the path of death. If one nourishes the primordial harmony, penetrates the essence of flavors, and makes the spirit clear and the qi refreshing, reaching a state of not sleeping day or night, relying solely on void condensation and quiet rest, there is no goodness that can surpass this.

   Explanation: Being awake aligns with Yang, and sleeping merges with Yin. If one is awake more, it indicates strong Hun; if one sleeps more, it indicates strong Po. Strong Hun leads to vigorous vital energy, while strong Po leads to strong energy of death. If one constantly maintains the state of Yuanhe (primordial harmony), free from desires and attachments, one can achieve clarity of spirit and freshness of qi. To reach the state of not sleeping day or night, one can only achieve this through void condensation and quiet rest.

   Analysis: The saying "when the spirit is full, one does not desire sleep" follows this same principle. In the Daoist path, when the Hun and Shen are strong, one naturally feels energetic and can get by without sleep. However, it is important to note that this is a result of strong Hun, not a directive to deliberately avoid sleep or pretend to have strong Hun; these are two completely different things.

   To achieve a full spirit, one must practice "void condensation and quiet rest." This is a cultivation method where one reaches extreme stillness, leading to natural condensation in the void. This nourishes and replenishes the Hun and Shen, making them full, thereby naturally reaching the state of not needing sleep.

   For ordinary people, one must still sleep when necessary, because without sleep, the Hun and Shen cannot be replenished during rest. However, sleeping too much leads to strong Po, and if Po becomes too strong, it will harm the Hun and Shen.

   For example, when people sleep, sleeping too little makes one tired, and sleeping too much also makes one tired; this is the principle at work.

   As for the lineage of sleep meditation in Daoism, this is a state of seeming sleep but not quite sleep, merely a method of nurturing the spirit in stillness. One can refer to: "The ears hear nothing, the eyes see nothing, the mouth speaks nothing, the mind has no abode, the breath is not forced, the body does not move. Only a spark of primordial spirit and primordial qi remains, clinging to each other like a single ember in a furnace, continuous yet faint, existing and non-existing, becoming pure and skilled over time." Furthermore, in Chen Tuan's (Old Ancestor) sleep meditation method: "The dragon returns to the primordial sea, the Yang hides within the Yin. People hibernate like dragons, but I hibernate my heart. Silently concealing its function, breathing deeply. Lying on white clouds, the world knows no sound." There is also the verse left by Patriarch Lü: "High pillows on Zhongnan, ten thousand worries empty; The Sleep Immortal often lies among white clouds. Dream souls secretly enter the Yin-Yang cavities, hidden breathing secretly applies the work of creation. Who knows the true secret hidden in chaos? The Daoist first must learn to be foolish and deaf. The hermit of Huashan left the method of sleep, now openly proclaimed to awaken the public."

  This type corresponds to what is said in the Can Tong Qi: "In sleep and wakefulness, the spirit embraces each other, timing the waxing and waning to await survival and death." It is also a method of dissipating Po and refining the spirit. Therefore, this method must only be practiced when the spirit is clear and the qi is refreshing, and not when one is drowsy; one must distinguish clearly.

  There is another lineage of dream cultivation methods, starting with observing dreams, seeking unity between the dreamer and the dream, and finally viewing the world as a dream. This cultivation is actually a method for refining the Yin Shen (Yin Spirit), belonging to the refinement of Po, and is not suitable for those on the path to immortality; one should reflect on this independently.