But that is not the goal; they are only powers that develop as a result of this: the goal is Samadhi. It is the last state of the entire process. When you attain to Samadhi, there is a tremendous intensity of concentration, so much of intensity that everything else is abolished. There is such an identity between you and the object! In fact there are cases of people who go into trance when externally they become so unconscious, that even to awake them is difficult; from sleep it is easier to awake somebody, but this is such a state that even to awake them is difficult. Sometimes you have even to inflict some pain on the body to make the body awake and to bring back the individual to the ordinary consciousness.
It is said of Sri Ramakrishna, when he use to go into Samadhi, to bring him back you had to shout in his ears and then try to bring him back. But this is a state of intensity; in that state…there are two stages, savikalpa and nirvikalpa: savikalpa is that there is still a seed of thought; nirvikalpa is one in which there is no seed of thought. It is such a silence, supreme silence, that you can remain for ever in that silence: even if the body is left in that condition, the consciousness which has attained that silence remains, and then you are liberated from the entire movement of the world. Through Samadhi you enter into a complete immobility of consciousness.
Yoga system accepts the distinction between Purusha and Prakriti as in Sankhya; therefore it says that when you concentrate upon an object, you can concentrate upon Purusha; among many objects, you can also take Purusha as one of the objects. And if you concentrate upon Purusha, then you realise the complete immobility and silence of Purusha, and you become liberated. Or, Yoga philosophy departs from Sankhya to some extent and says there is also the Lord. In the Sankhya proper it is nirīṣvara, but in Yoga, Yoga accepts the existence of God as a controller of the world; so it also says that you can devote yourself to the Lord, and if your are in Samadhi, if you go into that Samadhi, you can become united with the Lord: īśvaraḥ praṇidhāna, surrender to the Lord; īśvaraḥ praṇidhāna, is also one of the Niyamas in the yogic philosophy.
You remember I gave you five Niyamas: Shaucha, Shama, Tapa, Svadhyaya, Santosha. Now, Svadhyaya has an option, either so Svadhyaya or īśvaraḥ praṇidhāna; this is also one of the five rules of the yogic philosophy. This is in brief the entire net of the philosophy that is called Yoga.