Khândogya Upanishad: VII, 21

TWENTY-FIRST KHANDA. 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.