yoga can be mastered over a period of three to four years. Mastering the breath The text dedicates the largest number of verses to the discussion of breath and breath exercises. Yajnavalkya dedicates significant amount of text to explain the art of mastering each stage of breathing, that is inhalation, exhalation and stoppage between the two. Each stage is discussed in terms of its nature, speed, duration, depth on its own and relative to the other stage of breathing, regulating these at will during asanas meant for cleansing body or mind. In order to keep time for each stage without distraction, he recommends silently reciting time-measured mantras or sound beats to help measure each stage and thus establish progress during the yoga. The mantras for internal time measurement mentioned include Pranava (Om), Gayatri with Vyahritis, or Gayatri with Siras. The text classifies three levels of breath regulation, namely Puraka (पूरक, satisfying), Kumbhaka (कुम्भक, prominent) and Rechaka (रेचक, purging). The Puraka exercise is shortest and counts twelve moments (matras, music beats); the Kumbhaka is medium and stretches over twenty-four moments, while the Rechaka is highest lasting thirty-six moments. The text then describes various combinations of Puraka, Kumbhaka and Rechaka in various asanas for the purposes of energizing the Nadis and cleansing the body, asserting that, when mastered, Prana, Apana, Samana, Udana, Vyana and other vital airs help gain endurance, calmness, measured speed, ascension and inner healing. The text says that Pranayama exercises have therapeutic powers. Yajnavalkya describes Sanmukhi mudra, Kevaka kumbhaka and Sahita kumbhaka in chapter 6, asserting that the best exercises are those that make one feel lightness in the body and relaxation in the mind. Meditation Chapter 7 discusses the fifth limb of yoga, Pratyahara, which it says is of five forms. This stage is one where the focus of the mind shifts from external stimuli received by sensory organs to various levels of internal awareness. The theory of Marma (joints) is presented, and 18 vital points inside one's body are listed that can be used as focal points to help initial stages of the meditative exercises. Verses 1–10 of chapter 8 elaborate on the practice of Dharana or meditation to train the mind in the consciousness of the self. The five elements in the universe correspond to five body functional systems, and that systems are gods residing within the human body. The next level of meditation is to