Yoga Sutra - Sādhana Pada 2.21
तदर्थ एव दृश्यस्यात्मा ॥२१॥
tat-artha eva-dṛśyasya-ātmā ||21||
The nature of the seen is only for the purpose of that (purusa).
The essential nature of that which is seen is exclusively for the sake of the seer.
The seen, that is, the knowable—buddhi (and ultimately prakṛti herself)—exists only for the sake of puruṣa, who is the seer, reiterates Vyāsa, and is thus dependent on another, not on itself. As II.18 informed us, the purpose or function of the seen, prakṛti, is to provide either experience or liberation to puruṣa, and this purpose is fulfilled when experience or liberation has been attained. The nature of experience consists of pleasure and pain, and pleasure and pain are not conscious of themselves; they are experienced by an other. This other is puruṣa. Therefore, the purpose of the seen is not for itself but for the seer, just as the purpose of a bed, continues Vijñānabhikṣu, is for the sleeper, not for itself. Or, as Vācaspati Miśra puts it, the relationship of puruṣa and prakṛti is like that of the king and his possessions.
Since prakṛti has nothing more to do once its purposes are fulfilled, asks Rāmānanda Sarasvatī rhetorically with an eye to the next sūtra, does this mean that, deprived of its function, prakṛti would no longer be perceived? Might it even cease to exist?