Sri M said....

In the Mundaka Upanishad, knowledge is mentioned as ‘vidya’ and has been divided into ‘Para-vidya’ and ‘Apara-vidya’. In ‘Apara vidya’, all the Vedas and Ved-angas like astronomy, grammar and so on are included. The Upanishad defines ‘Para-vidya’ as that which leads purely to the realization of the Supreme Truth. Subsequently, it calls those teachers, who are experts in ‘Apara-vidya’ with no knowledge of ‘Para-vidya’, as ‘Andhai naiva niyamaana yath andhaaha’, meaning the blind leading the blind.