Yoga (or, the practice of reuniting our consciousness with the deeper consciousness of the Godhead), it explains, is "the control of thought-waves in the mind." The methodologies of all the branches of Yoga, even the now-popular hatha yoga, are ultimately aimed at achieving this reunion.
"The mind seems to be intelligent and conscious," Isherwood and Prabhavananda note. And, yet, "Yoga philosophy teaches that it is not." Our ordinary mind - self-consciousness, or the "ego" - in fact, "borrows" its seeming consciousness and intelligence from the Godhead within us, from the Atman.
In a powerful image, Isherwood and Prabhavananda explain how the true nature of the mind (the Atman) is obscured by our habitual ideas and patterns of thought (the samskaras, or 'sheaths' that obscure the Atman) and how spiritual practice and meditation clarifies the mind and reunites it with the Godhead within each of us. They, as many traditionalist teachers before them have done, compare the mind to a lake.
"If the surface of a lake is lashed into waves, the water becomes muddy and the bottom cannot be seen. The lake represents the mind and the bottom of the lake represents the Atman.
When Patanjali speaks of "control of thought-waves," he does not refer to a momentary or superficial control. . . . We have to do something much more difficult - to unlearn the identification of the thought-waves with the ego-sense. This process of unlearning involves a complete transformation of character, a "renewal of the mind," as St. Paul puts it.
"The yoga aspirant does not waste his time wondering where his samskaras come from or how long he has had them; he accepts full responsibility for them and sets about trying to change them."
- Isherwood and Prabhavananda, page 21.