|Chapter 2: Contents of the Gita Summarized|
karma-jam buddhi-yukta hi
phalam tyaktva manishinah
padam gacchanty anamayam
By thus engaging in devotional service to the Lord, great sages or devotees free themselves from the results of work in the material world. In this way they become free from the cycle of birth and death and attain the state beyond all miseries [by going back to Godhead].
Krishna provides in this verse one of the detentions of liberation. The term liberation literally means "to become free." It can be used in various contexts and is thus the cause of some confusion. Liberation could mean freedom from life on the Earth planet, in other words ascending to the heavenly plants (svarga loka). Liberation could also mean freedom from the modes of material nature, which is a state, called Brahma-nirvana or situated in the Brahmana. Liberation could also mean freedom from the cycle of birth and death, which means going back to the spiritual abode (Vaikuntha) and never having to take birth again.
One can ascend to the heavenly planets by the dint of pious activities. However, once the stock of these activities is exhausted, the soul is forced to fall back into the lower planets. By the force of jnana, one can detach from the cycle of karma and reach the stage of Brahma-nirvana. However, since it is the nature of the soul to be active and seek enjoyment, eventually it will tire of the nothingness in this stage and fall back into the material cycle.
The liberation that Krishna is talking about here does not fall in the above two categories, which are temporary and partial. He talks about liberation from the cycle of life and death, from the modes of material nature, from the material world and from all form of miseries. This form of liberation is complete and all-inclusive. It is only accessible to one who engages in the service of the Supreme Personality of Godhead.
Srila Prabhupada explains, "The miseries of life, namely birth, death, old age and diseases, are present everywhere within the material world. But one who understands his real constitutional position as the eternal servitor of the Lord, and thus knows the position of the Personality of Godhead, engages himself in the transcendental loving service of the Lord. Consequently he becomes qualified to enter into the Vaikuntha planets, where there is neither material, miserable life nor the influence of time and death."
Please read the Sanskrit Verse and the Prabhupada's Purport.