The Canopy Ruler is one of the ritual implements used in Taoist ceremonies to stabilize the altar and ward off evil, and it should not be used indiscriminately. It is typically employed when establishing a ritual altar. In the altars of certain Taoist lineages, it is common to see items such as peach wood swords, command flags, command arrows, command tablets, the Canopy Ruler, and altar-stabilizing wooden blocks. Some also place other implements like ghost-torturing sticks. (The claim on Baidu Baike that Taoist altars must typically display at least these items is incorrect; this practice belongs only to a very small minority of lineages. Many other orthodox lineages, depending on their specific transmissions, do not require these items on most altars.)
The Canopy Ruler should be used in conjunction with the Northern Emperor Canopy Demon-Subduing Great Dharma, the Mixing Heaven Flying Capture Four Saints Demon-Subduing Great Dharma, the Shangqing Child-First Five Elements Mansion Jade Register Orthodox Dharma, the Purple Court Pursuit, Punishment, Supplementation, and Severance Great Dharma, the Northern Yin Fengdu Tai Xuan Demon-Subduing Black Law for Collecting Evil Sorcerers, the Northern Yin Fengdu Tai Xuan Demon-Subduing Black Law for Spirit Writing, and the cultivation of the Canopy Mantra. Among these, the Canopy Seal and Canopy Talisman are also extremely important. The Canopy Ruler is a crucial implement for executing Canopy rituals. Historically, it was primarily passed down secretly within the Shangqing school of Taoism, and later transmitted through various lineages by Patriarch Deng Ziyang. When the merit and virtue of its cultivation are fulfilled, one can achieve: 'Evil ghosts, demons, and spirits, fierce and vicious monsters, will flee upon hearing its name. Ten thousand illnesses and a thousand disasters will be cured upon hearing its words. It can cause dead wood to bloom, dry wells to gush with spring water, break the five ghosts and epidemics, subdue the six heavens' residual qi, half-sky five yu, mountain spirits, and demon foxes, cutting off their influence through the mantra. Using the seal to lock ghost caves, executing dragons and water spirits, communicating through petitions without obstruction, swallowing, wearing, pasting, and stabilizing with it grants the power to revive the dead. Upon completion of the work and fulfillment of the practice, one ascends to immortality riding the ruler and wearing the seal.'
Furthermore, in the Tang and Song dynasties' Canopy rituals, many mantras were derived, including the Canopy Calming Mantra, Great Fire Bell Mantra, Canopy Demon-Slaying Mantra, Canopy Heart Seal Mantra, Canopy Ancestral Qi Mantra, Canopy True Form Ghost-Slaying Mantra, Secret Canopy Mantra, Canopy Demon-Extinguishing Mantra, Great Canopy Mantra, Canopy Invocation Mantra, Canopy Ordinance Mantra, Canopy Divine Ruler Mantra, Canopy Transformation Mantra, Canopy Mouth-Cleansing Mantra, Canopy Life-Preserving Mantra, Ordinance Canopy General Mantra, Added Phrase Canopy Mantra, Canopy Invocation Mantra, Summon Six Palaces Demon King Mantra, Dispatch General Mantra, Canopy True Lord Mantra, Summon Marshal Sang Mantra, Life-Preserving Mantra, Summon Four-Eyed Old Man Mantra, Battle Evil Mantra, Gongcao Mantra, Hunyuan Qi-Distribution Mantra, Ghost-Examining Mantra, etc.
According to historical records: The Gongyuan (Imperial Examination Hall) in Lin'an was full of strange creatures, and officials and soldiers often saw them. In the autumn of the first year of Qiandao, during the provincial examinations, Huang Zhongbing Jun, Hu Changwen Yuanzhi, Rui Guorui Hui, and Chang Yugong Yong served as examiners. Liu Rong, the head of the State College, was alone in a room, suffering from malaria and sleeping during the day. A man and a woman entered hand in hand, inviting Liu Rong, saying, 'It is very enjoyable outside the door. Why do you sit alone like a block?' Liu Rong did not respond. They forced him to get up from the bed. Liu Rong sat up and recited the
Canopy Mantra. After just a few sentences, the two people hurriedly left. Yugong's servant went to the central hall to fetch soup and felt as if someone were walking rapidly behind him. He was somewhat startled and dared only to look back after seeing the light from the hall. He saw a flock of white geese, which disappeared when he shouted at them. Changwen's young clerk passed through the middle behind the hall and encountered a woman with a high bun and elaborate dress, leaning on the railing and sitting, but her feet were not visible. When he looked forward slightly, she had already vanished. The night watchman said that every night they would see this ghost coming and going.
In the
Supreme Primordial Heavenly Lord's Scripture on the Northern Emperor's Demon-Subduing Mantra, it is recorded: The Northern Emperor said: If sealing mountains and rivers, ordaining ancient temples, summoning the gods of the Five Sacred Mountains, hearing about future events, moving mountains and overturning seas, or driving away spirits and demons, take this talisman of mine, place it on a mirror, write it with cinnabar, and hang it above the Seven Stars Altar, two hundred feet away from the altar. Recite the Canopy Mantra on the altar, and the spirits and ghosts will appear before you. In an instant, future events will be revealed.