Kaayena manasaa buddhyaa kevalair indriyair api;
Yoginah karma kurvanti sangam tyaktwaatmashuddhaye.
Yogis, having abandoned attachment, perform actions only by the body, mind, intellect
and also by the senses, for the purification of the self.
In this sloka Lord Krishna talks about the qualities that a yogi should have. We have already learnt the meaning of a yogi. A Yogi is the unifier. Here Lord Krishna says that, after abandoning or leaving the attachment to different things, a yogi performs his actions through his body, mind, intellect and senses. That means the yogi has to first unify mind, senses and intellect with his body. It is the body that performs the actions but those actions should be directed by mind, intellect and senses working together. Only then that person will attain the purification of the self, says Lord Krishna.
Extending to Mankind’s life!
The point we need to understand here is purification of the self. What exactly you mean by that? Purification of self means making one’s self equal to that of Brahman. According to Upanishads the purest thing in this universe is Brahman. A person will slowly start purifying his own self step by step, so that his soul reaches to the level of purity that is equal to Brahman. It is possible when he controls his body from doing wrong actions, controls his senses from getting the urge to do wrong things and controls his mind so that it doesnt think about doing wrong things and finally expands his intellect so much that his body, mind and senses get engulfed in them. That ultimately leads to purification of his self.
How does one do it? It is only possible through unification which is also called Yoga. Yoga here means meditation. When you go into deep contemplation by closing your eyes your body will slowly come under control. It stands still without moving an inch. Then your senses one by one will come under control. You stop seeing, hearing or feeling anything which is outside. Your mind will stop thinking about other things and only concentrates on what you are doing. This is called the unification of body, senses and mind. When intellect adds to it, they all become one and such person is called as Yogi or the great unifier. This unification leads to purification and that is the way for a person for his soul to reach Brahman.