Patanjali"s Yoga Aphorisms, or Yoga Sutras, are rather like algebraic formulas. They are hardly comprehensible without a commentary. The commentary of Bhoja Raja is the clearest and simplest one known, and thus was chosen by the first translators of the Yoga Sutras. The better known commentary by Vyasa, and its sub-commentaries, are more complex and difficult. Here is the first, and still the only complete translation of Bhoja Raja"s commentary. Although not an easy text, it provides what is perhaps the most comprehensible description of the ancient science of meditation found in the Yoga Aphorisms of Patanjali.