Apara Vidya is the knowledge other than the supreme knowledge of Reality. In Mundaka Upanishad, the householder Saunaka approaches the sage Angiras and asks – Adorable sir, what is it by knowing which everything else is known? Replying, Angiras talks of two kinds of knowledge – para and apara. Taking up apara first, he tells Saunaka that is consists of Rig Veda, Yajur Veda, Sama Veda and Atharva Veda, besides the science of Deeksha (pronunciation), kalpa (code of rituals), vyakarana (grammar), nirukta (etymology), chandas (meter) and jyotisha (astrology). This system of knowledge, (vidyasthana) covers Vedas and Vedangas.
Para vidya is the realization of the Supreme Self which is the
goal of the various knowledge disciplines enumerated above. This is brought out
forcefully in the Narada episode of Chandogya Upanishad. Narada tells
Sanatkumara of the vast knowledge of mundane arts (apara vidya) he has acquired
but confesses, ‘I am still not happy; I have no knowledge of Self, knowing
which one goes beyond sorrow.’ On Narada’s pleading for help to ‘cross the
ocean of sorrow’, Sanatkumara tells him of bhuma, the Infinite (or the
Biggest). The Infinite is the Brahman by knowing which everything else is
known.
Angiras also explains para vidya as the knowledge of the
immutable – aksharam. It is not mere knowledge in the ordinary sense but
realization of Brahman, the source of all – bhutayonim.