"Only those who can clearly differentiate between the two aspects of their nature, the real self and the illusory self, can work intelligently. This has been well expressed in the Yoga Sutras of Patanjali. "Experience (of the pairs of opposites) comes from the inability of the soul to distinguish between the personal self, and the purusa (or spirit). The objective forms exist for the use and experience of the spiritual man. By meditation upon this arises the intuitive perception of the spiritual man." Book III.35. The forty-eighth Sutra in the same book gives a statement covering a later stage of this discriminative realisation. This discerning quality is fostered by a re-collected attitude of mind, and by careful attention to the method of a constant review of the life. Some Basic Assumptions p. 54"