The term means knowledge received by the student ‘sitting close to’ the teacher. Education involving the student ‘sitting close to’ the teacher means the most intimate student-teacher commu­nion. The higher the knowledge sought, greater is this communion and greater the silence accompanying the knowledge-communication.

These values reach their maximum when the knowledge that is sought and imparted is of the highest kind, namely, atmajnana or brahmajnana, knowledge of the Atman or Brahman.

Reference: The Message of the Upanishads by Swami Ranganathananda (p.12,13)