By constraint on sense-perception, their essential nature, ego-sense, their interconnectedness and purposefulness, mastery of the sense organs is attained.
This exercise is along the same line as constraint on the Elements in which mastery is obtained.
Here one gains mastery of the senses not by temporarily withdrawing them such as Pratyahara or sense withdrawal being the fifth anga of Patanjali’s ashtanga yoga (8 limbs), but by absorption in them, being total in them through becoming aware of their essential nature, how the ego-sense relates to them, the interconnectedness of all the senses and what their purpose are. Awareness here is the key to mastery and not repression or suppression.
The mind is energy which perceives matter through the senses. It is the mind that projects the light of consciousness through the senses in order to perceive the world. The Seer, being the protagonist and the theme behind and at the heart of the Yoga Sutras, is consciousness itself as Pure Awareness.