“The basic doctrines of the Vedanta and Saukhya systems are monistic Pantheism, intuition as the supreme means to reach truth, metempsychosis, the world of sense is only a very little part of the category of things, the theory and method of salvation strictly intellectual. These systems developed from the Upanishads.
The final development is the Yoga. Yoga, i.e. “one who fits himself, or exercises”, refers to the exercises practiced to free the soul from the body, which to it is like a string to a bird. Some of these exercises were: to rid one’s self of moral faults (though the masters do not agree as to what these faults are); to sit in certain painful postures, check the breath, and reduce thought to a minimum by staring at the tip of the nose; to place the soul in a particular part of the body, and so gradually acquire mastery over it, or, rather, let the soul, the true self, acquire mastery over the body; to stave and learn to subsist on air or even without it; to concentrate thought by meditation, i.e. to think of nothing. Thyana, the highest state of which is the cataleptic trance samadhi, in which the mind is suppressed but the soul is in full activity. In this state the person is a mahatma, i.e. master-soul and can enjoy a temporary release from the body which it leaves to go roaming about, performing wonderful feats on material nature and controlling other less powerful souls. This latter was the secret of the Yoga’s real power and was supposed to be done by a transfer of soul. When the soul re-enters the body, the Yoga wakes and is like other people.
By repeated exercises the soul can become so strong that is secures perpetual release from the body, thus, according to the older Yoga teaching, it flies to heaven where it enjoys great happiness, riding in a celestial car attended by lovely women and music; but with the latter Yogas, on breaking all bodily bonds it formed immediate absorption into the Supreme Soul.”
newadvent.org/cathen/14626a.htm
