Vidya & Shiksha both are necessary for a human that has manifested in physical form. Shiksha seeks furtherance through sensory drivers whereas Vidya transpires within an observatory at the depths of human understanding. Shiksha facilitates human life & Vidya evolves human existence. The knowledge of Upanishads is Vidya. As the great masters convey that the pursuit of knowledge under Vidya is a cooperative endeavor. The teacher & the student both seek removal of taint (अकल्मष) so that they access esoteric revelations respectively. And that is the objective of Upanishads.