Book of Sui: Treatise on Classics and Books – Preface to Taoist Scriptures states:

The Taoist scriptures speak of the Celestial Worthy of Original Commencement, who was born before the Great Origin, embodies the spontaneous pneuma. His essence is characterized by unfathomable emptiness and boundless profundity, transcending all limits. Similar to the records in Buddhist scriptures, the heavens and earth would decay, and the cosmic kalpas would reach their end someday. The body of the Celestial Worthy exists eternally, undying and unceasing. Each time the cosmos is reborn, he manifests either atop the Jade Capital or in the Field of Qiongsang, imparting secret teachings to start the kalpa and deliver salvation. The opening of a kalpa has occurred multiple times throughout history. There are specific kalpas  named Extended Vigor, Vermilion Brilliance, Draconic Magnificence, and Opening Luminary, with each one separated by 41 billion years – a numerological expression of cyclical renewal. These teachings are transmitted to Celestial Immortals of the Highest Rank, including the Most High Lord Lao, the August One of Heavenly Perfection, the Five Emperors of the Five Directions, and celestial officials, who pass them down through lineages and made inaccessible to ordinary mortals.The scriptures told by the Celestial Worthy originated spontaneously from the pneuma of Original Unity, neither crafted nor composed, enduring eternally like the Celestial Worthy. When the cosmos is intact, the scriptures remain hidden; the characters reveal when the cosmic kalpa begins. The scriptures consist of eight characters, embodying Dao’s profundity, and is therefore named the Celestial Book. Each character measures one zhang in size, shines brightly from eight corners, even the celestial immortals cannot behold them directly. To initiate a cosmic kalpa, Celestial Worthy instructs the August One of Heavenly Perfection to translate celestial language into forms intelligible to beings. Such teachings then descend hierarchically from Perfected Ones to immortals and finally to humanity, unveiling the Embodiment of the Dao.