The Relation of Yoga and the Upanishads!
According to Prof. Ranade, “We thus see that if we just add the Yama and Niyama of later Yogic philosophy to the various elements of Yoga, as mentioned in the old Upanishads, namely, the Asan, the Pranayam, the Pratyahar the Dharana and the Dhyana, all as preparatory to Samadhi, we have the full-fledged eightfold scheme of Yoga or the way to spiritual realisation.” Most of the Yoga philosophy is found in the Svetasvatara Upanishad.
The relation of Yoga and the Upanishad is also found in the following:
(i) Asan, Pratyahar, Pranayama, Samadhi:
In the Svetasvatara Upanishad one finds the description of Asan, Pratyahar, Pranayam, the physical effects of Yoga and Samadhi.
Dharana has been mentioned in the Kathopanisad, where it has been taken as the highest stale of Yoga and the balance of senses, mind and intelligence.
Dhyana has been described in the Svetasvatara Upanishad, where one is asked to search for God in the heart by concentrating upon Him.
The God of Yoga has been described in the Kathopanisad where he is said to be beyond the worldly miseries, just as the sun is the eye of the world which is beyond the defects of the eyes.”
(v) Physical aspect:
The physical aspect of Yoga has been described in the Kausitaki and the Maitri Upanishads.