“We all talk of Yoga – we are not sure what Yoga means.” – Dr. Jayadeva Yogendra
The word yoga seems to have acquired such a prolific significance all along the history and development of its various practices even from the earliest period of the Vedas that it is very difficult to associate or determine its exact meaning within the limits of any particular philosophy. For example, during the period of the Rgveda and in such later Vedic works as the Brahmanas and the Aranyaks, the word yoga meant ‘achieving the unachieved,’ ‘harnessing’, ‘controlling’, ‘yoking’, ‘connection’ and the like.
The word also has another derivation “Yogya”, which is probably an old word of the Aryan stock used in later Sanskrit literature of the Upanisads. Similar to the old metaphor of controlling or yoking the senses which were considered as uncontrollable horses, Yoga as an effort was probably suggested by a metaphor taken from the stretching of a bow.
During the period of the early Upanisads, however the word Yoga passed through a variety of meanings and interpretations. In the Katha Upanisad (VI, II) we are told that Yoga is the firm restraint of the senses, Le., when the senses are controlled with the mind and when the mind becomes steady, that controlling and keeping steady of the senses and the mind is yoga. This was followed by an important addition and modification of the original idea, viz, the control of the Prana as representing the main process of Yoga.
Yoga Defined
Again the idea of absorption and union with Supreme Being which occurs in the Upanisads-especially in the Taittiriya(X), Mundaka(II, 4) and Katha (IV, 15)- seems also to have greatly influenced the later yoga interpretations, In the Maitrayaniya- Upanisad, however, Yoga is defined as the joining of the Prana and Om and also as the uniting of the senses, the mind and the Prana by the removal of all sensual knowledge (Bhava). It also holds that Yoga is one-pointedness and unity (yogam laksayatyekatvamiti). In the commentary called Dipika of Ramatirtha on the same Upanisad, we are told that as relative to the control of the mind- functioning’s, the Yoga proposes the following, viz., the six accessories (cittaaikagrayasadhanasyaprayogavidhi).
In the Mahabharata, yoga is defined as the unity with the source (in the sense of Layayoga). At another place it advocates that the Yogins are those are well connected (with the object of their knowledge). It also refers to the concentration of the mind as Yoga (195, 528)