The fifteenth chapter of the Bhagavad Gita is Purushottama Yoga. In Sanskrit, Purusha means the All-pervading God, and Purushottam means the timeless & transcendental aspect of God. Krishna reveals that the purpose of this Transcendental knowledge of the God is to detach ourselves from the bondage of the material world and to understand Krishna as the Supreme Divine Personality, who is the eternal controller and sustainer of the world. One who understands this Ultimate Truth surrenders to Him and engages in His devotional service.
The Supreme Divine Personality said: They speak of an eternal aśhvatth tree with its roots above and branches below. Its leaves are the Vedic hymns, and one who knows the secret of this tree is the knower of the Vedas.OPEN VERSE
The branches of the tree extend upward and downward, nourished by the three guṇas, with the objects of the senses as tender buds. The roots of the tree hang downward, causing the flow of karma in the human form. Below, its roots branch out causing (karmic) actions in the world of humans.OPEN VERSE
The real form of this tree is not perceived in this world, neither its beginning nor end, nor its continued existence. But this deep-rooted aśhvatth tree must be cut down with a strong axe of detachment. Then one must search out the base of the tree, which is the Supreme Lord, from whom streamed forth the activity of the universe a long time ago. Upon taking refuge in him, one will not return to this world again.OPEN VERSE
Those who are free from vanity and delusion, who have overcome the evil of attachment, who dwell constantly in the self and God, who are freed from the desire to enjoy the senses, and are beyond the dualities of pleasure and pain, such liberated personalities attain my eternal abode.OPEN VERSE
Neither the sun nor the moon, nor fire can illumine that supreme abode of mine. Having gone there, one does not return to this material world again.OPEN VERSE