Exploring the Yogasutra is not for the novice. Daniel Raveh's exploration mainly addresses the psychology and epistemology underlying Pantanjali's Yogasutra; but he also discusses the difficulties of translation, particularly translating an ancient text in a dead language of a foreign culture into a modern idiom. One can hardly expect that the original meanings of the words will be replicated simply and concisely in a modern language; however, one might hope that if the ideas under discussion are eternal and universal truths that any relatively well-developed language would provide some way of expressing those ideas. Since there clearly are difficulties in translating the Yogasutra, one is led to conclude either that it does not reach what is eternal and universal in human experience or that our manner of understanding human experience is variable and requires a more or less significant reframing of how we understand experience. Anyone remotely sympathetic to comparative religion will opt for the latter explanation and seek help in reframing experience. Raveh's book attempts to illuminate the assumptions about the structure of mind that are required for this reframing in order to appreciate yogic processes and yogic knowledge.
The most significant assumption is that mental activity is associated with two concepts: prakriti and purusa. Raveh defines prakriti as "the manifest and nonmanifest dimensions of the world and worldly existence." In contrast, purusa is the metaphysical core of the self. Typically, Western psychology would associate mental activity with the latter and see the former as the external cause of mental phenomena; however, the Yogasutra and likely the entire yogic tradition, understands mental activity to be part of, or operating within, prakriti. Consequently, a higher yogic truth (or "truth-bearing yogic insight") can only be revealed when the yogi brings about a cessation of mental activity.
Raveh makes an important contribution to the epistemology of yoga when he compares two sutras of the Yogasutra. His observation helps us understand the nature of yogic knowledge that is made possible when mental activity ceases. Raveh translates Yoga Sutra 1.7 as "valid knowledge is based on sense perception, inference and reliable testimony." Here, Raveh notes that "valid knowledge" is based on mental activity that lies within prakriti. It is conventional knowledge. He then translates Yoga Sutra 1.49 as "(ritam-bhara prajna or truth-bearing yogic insight) is essentially different from knowledge based on reliable testimony and inference as it touches on particulars." Notably, truth-bearing yogic insight is not said to be essentially different from sense perception. Raveh concludes that truth-bearing yogic insight is like sense perception as they both "touch on particulars," but it is different in that it does not operate within the realm of prakriti. Together, these two sutras provide us with an understanding of the form of knowledge that the yogi seeks: a direct perception of particulars that are not of the manifest or nonmanifest dimensions of the world or worldly existence.
To achieve yogic knowledge, Pantanjali recommends a path composed of "eight limbs." The eight limbs are yama (ethical restraints), niyama (personal discipline), asana (yogic postures), pranayama (breath control), pratyahara (withdrawal from the sense world), dharana (concentration), dhyana (meditation), and samadhi (total meditative absorption). According to Pantanjali, by following this path -- particularly by practicing the final three stages of meditation -- the yogi can achieve a final and irreversible escape from the delusion and suffering that is this world.
The final chapter of Exploring the Yogasutra is not written by Raveh, but by Daya Krishna (1924-2007), author of Indian Philosophy: A Counter Perspective. Raveh is deeply impressed with Daya Krishna's treatment of Pantanjali's Yogasutra. It is Daya Krishna's approach to the Yogasutra which motivates Raveh's work. The most important insight that Daya Krishna provides is that samadhi cannot be the ultimate goal of the yogi. Samadhi is commonly understood as an ultimate, unworldly state that is irreversible. Following Daya Krishna, Raveh points out that entering a state in which one cannot return is a limitation on the freedom of the yogi, and that perfect freedom requires that the yogi be capable of both entering and returning from samadhi (or the meditative state that is samadhi, save its irreversibility.)
This view prompts two observations, the first of which Raveh does not seem to take seriously. First, samadhi should be understood as a meditative state which cannot be achieved perfectly in practice; second, the motivation to return from samadhi appears to be similar to the motivations of the Buddhist bodhisattva. The first two states of meditation, dharana and dhyana, clearly seem to admit of degrees of achievement. One can concentrate on external objects more or less effectively and one can more or less focus on one's mental processes. If one accepts that samadhi is a state in which one becomes more or less unaware of the distinction between the subject and the object of meditation, then irreversible samadhi is merely the limit that the yogi may approach, but not fully achieve, in the final stage of meditation (samadhi). On this account, samadhi is both an irreversible state that one does not achieve and a meditative state beyond dhyana that yogis can experience. The goal remains irreversible samadhi or total meditative absorption, but pursuing this goal does not preclude the return of actual yogis from the state of samadhi.
The second obvious observation is that Daya Krishna (and Raveh) appear to be reprising the reformation that took place in the Buddhist tradition when Mahayana Buddhism broke from Buddhism's early form. The yogi who exercises freedom by returning from the state of samadhi is like the bodhisattva, who renounces perfect enlightenment to bring salvation to all sentient beings. Raveh recognizes that the Yogasutra stands as evidence that Patanjali himself must have recognized the value of returning to enlighten others. The Yogasutra is, after all, a guidebook to yogic knowledge.
Exploring the Yogasutra is not easy reading. This is due mostly to Raveh's frequent use of Sanskrit terms without providing the necessary context for understanding them. It is a curious feature in that Raveh is acutely aware of the difficulties in translation. It is almost as though he is writing for an extremely erudite audience or he has simply given up on the difficult work of translation. Perhaps a little of both is true.
Finally, Raveh provide us with a highly readable translation of the Yogasutra, presented without interpolated commentary. Despite its textual difficulties, Exploring the Yogasutra is a work well worth reading.