The opposite of existence does not exist, because anything that exists is existence. Even what we call unconscious is illumined by consciousness. Shiva Prasay is in meditation at any point of time, one shifts, one's focus, very spontaneously from each to some joyful, magical light. Pure consciousness never comes and goes, it reveals that which comes and goes. We should put effort to stay with the sense of I am, as every moment, correct.
Swami Sarvapriyananda teaches the Katha Upanishad, one of India's most revered texts which is also a part of the Vedas. It is a collection of philosophical poems representing a conversation between the sage Naciketas and Yama (god of death). They discuss the nature of Atman, Brahman and Moksha(liberation).