In Indian philosophy, Yoga is among other things, the name of one of the six āstika philosophical schools. The Yoga philosophical system is closely allied with the dualism premises of Samkhya school. The Yoga school accepts the Samkhya psychology and metaphysics, but is considered theistic because it accepts the concept of "personal god", unlike Samkhya. The epistemology of the Yoga school, like the Sāmkhya school, relies on three of six prāmaṇas as the means of gaining reliable knowledge: pratyakṣa (perception), anumāṇa (inference) and śabda (āptavacana, word/testimony of reliable sources).