The intellect, which was trying to do all these Vedantic enquiries, not the body because of these reasons. Vivekananda says, when the book of the mind opens, then you can dismiss with other books and have clarity within. This is basically is recommending meditation, yogic meditation. Here you can see the relation to yoga shittavriti niro dha, the definition of meditation in patanjali yoga.
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).