The Upanishads, Part 1 (SBE01): Khândogya Upanishad: VII, 21
The Upanishads, Part 1 (SBE01), by Max Müller, [1879]
1. 'When one performs all sacred duties 1, then one attends really on a tutor. One who does not perform his duties, does not really attend on a tutor. Only he who performs his duties, attends on his tutor. This performance of duties, however, we must desire to understand.'
'Sir, I desire to understand it.'
122:1 The duties of a student, such as restraint of the senses, concentration of the mind, &c.