The Scripture of the Mind Seal says, restore the (ancient) habits, and chaos will be brought into harmony; a hundred days and the work will be achieved. In general, setting up the foundation requires a hundred days before you have real light. You students are still working with the light of the eyes, not the fire of spirit, not the fire of essence or the torch of wisdom. When you have turned the light around for a hundred days, vital energy will naturally be sufficient for true yang to rise spontaneously, so true fire naturally exists in water. If you carry on the practice this way, you will naturally achieve intercourse and formation of the embryo. You are then in the heaven of unknowing, and the child thus develops. If you entertain any conceptual view at all, you will immediately enter a misleading path.
A hundred days of setting up the foundation does not literally mean a hundred days; one day of setting up the foundation does not mean one day. One breath of setting up the foundation does not refer to respiration. The Chinese character for true breath (息) is made up of the characters for Self (自) and mind (心). The Self (自) and the mind (心) sustaining it, is the true breath (息), which also refers to the original spirit, original energy, and original vitality. Rising and descending, parting and joining, all arise from the mind; being and non-being, emptiness and fullness, are all related to thoughts. The one true breath requires a lifetime to maintain, not only a hundred days; so a hundred days is also one true breath.
A hundred days is just a way to show how important the engagement of the true breath is. Engaging the true breath during the daytime, you benefit from it at night. Engaging the true breath at night, you benefit from it during the day. A hundred days of setting up the foundation is a teaching from the Gods. The sayings of the immortals all correspond to the human body and the sayings of real teachers correspond to students. This is the mystery of mysteries, which is inexplicable; you will know it when you see your essence. Therefore, students must seek the teaching of a true teacher. Everything that emerges naturally from the teacher’s essence proves effective.