Patañjali explains the practice of kriyā-yoga in sūtra I of the sādhana pāda, repeating the same ingredients as are found in the niyama disciplines, namely, tapas, svādhyāya, and Īśvara-praṇidhāna (discipline, self-study and devotion to God). This three-tiered definition clearly indicates the paths of karma, jñāna, and bhakti.