Vivekaraan Desai: "You must not go away with the idea that it is unknown or unknowable" The Atma is revealed in every knowledge, in every knowledge Pratibhoda Vidditam matam. Once we realize what the Atman is, there is no further desire to try to objectify and realize it as an object.
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).