Once ‘Saunaka’, Son of ‘Sunaka’, a great householder approached Angiras as prescribed and asked, ‘Venerable Sir, Which is that thing by knowing which all this becomes known? [Mundaka Upanishad 1.1.3]
To him he replied. Two kind of Knowledge are to be known, the higher and the lower. [Mundaka Upanishad 1.1.4]
Of these two, the lower knowledge is the Rig—Veda, the Yagur—Veda, the Sama—Veda, the Atharva—Veda, siksha (phonetics), kalpa (rituals), vyakaranam (grammar), nirukta (etymology), chhandas (m