This Sutra gives the most detailed explanation of the Buddha's teachings concerning the mind. It includes an analysis of where the mind is located, an explanation of the origin of the cosmos, a discussion of the specific workings of karma, a description of all the realms of existence, and an exposition on the fifty kinds of samadhi-concentrations, which, if we become attached to any of them, can delude us in our search for awakening. Also, in this Sutra, twenty-five enlightened sages explain the methods they used to become enlightened. Includes the Buddha's explanation of the Four Clear and Unalterable Instructions on Purity, how to establish a Bodhimanda, the Shurangama Mantra and its wondrous functions, and the twelve categories of living beings.