In the philosophical parts of the text, who is being compared to a parrot tied to a tube?

The text in Chapter 17 uses the metaphor of a parrot tied to a tube to describe the individual soul that has forgotten its true nature. This advice is directed at anyone who has become bound by their attachment to the physical body and deluded by the Maya of infatuation. The 'tube' represents the body and the 'parrot' is the soul, which is inherently free. The chapter explains that this soul has become confused by the bodily ego of 'I and mine,' and it is being urged to wake up, release the feet that are held tight, and fly high into the sky of self-realization to rediscover its true form as pure Brahman.