The Yogasūtras of Patañjali (200 B.C.) describes eight graded steps for controlling the mind. The last step is ‘samādhi,’ perfect concentration, resulting in a superconscious experience. This samādhi, again, is twofold: samprajñāta and asamprajñāta. In the former, the object of concentration is fully revealed and known. In the latter the mind settles down into itself without any vṛttis or modifications. Hence there will be no jñāna or knowledge of any object in particular.
This latter samādhi is also twofold: upāyapratyaya and bhavapratyaya. ‘Prat-yaya’ means kāraṇa or cause. ‘Bhava’ means saṁsāra or transmigratory existence. Since this latter samādhi does not give mokṣa or liberation, but causes bhava or transmigration, has been rightly called ‘bhava-pratyaya.’
Some yogis, endowed with apara-vairāgya or inferior spirit of renunciation, choose such objects as the pañca-bhūtas (the five elements such as earth and water), the indriyas (the sense-organs) or ahaṅkāra (the ego) and so on for their objects of meditation. When they attain asam-prajñāta samādhi through these, they attain a state which is similar to kaivalya or liberation. However, since they lack viveka-khyāti or the direct experience that the ātman (the Self) is separate from prakṛti (nature), they return to transmigratory existence after some time.