Viveka, Vairagya and Mokshuttham are the four qualifications of Vedanta. The sixfold discipline is desire for liberation or dispassion. In Samadhan meditation you need to develop a focus in your mind. Niddhidh Dhyasana (non-dual meditation) is also necessary at this level.
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).