Liberation (moksha) means freedom from material bondage and the cycle of birth and death. The Bhagavad-gita (2.51) teaches that one should perform duty without attachment to attain liberation, and (5.24-26) describes the state of liberation. The Bhagavad-gita (8.15-16) explains that the spiritual world is eternal, and (18.54-56) teaches that the highest liberation is pure devotional service. It is not merging into an impersonal existence but returning to one's eternal spiritual form and relationship with the Supreme. The Nectar of Devotion (Chapter 4) and Perfect Questions Perfect Answers (Chapter 3) teach that love of God is the perfection of liberation.