Taoism began in the late Eastern Han Dynasty, and it used Taoist theory to study the practice of alchemy and cultivation of immortals. If you are interested in the cultivation of Taoism, you can look at the collection series of Taoism.
If you like to study the highest knowledge of the mind, you might as well read Buddhist classics, such as Heart Sutra, Diamond Sutra, and Six Ancestors Tanjing, which can help you get deep into people's hearts and understand the truth of life in the universe.