In the Yoga Sūtras, citta is presented as the total “mind-stuff,” the subtle inner field in which all mental activity takes place. It is not a single function, but the entire psychic apparatus that belongs to prakṛti, distinct from the pure, unchanging awareness called puruṣa. This citta includes the sensory mind (manas), the discriminating intellect (buddhi), and the ego-principle (ahaṃkāra), so that perception, judgment, and the sense of “I” all arise within it. Because it is made of nature, it is inherently changeable and capable of taking on countless forms.

The Sūtras characterize citta primarily through its modifications, or vṛttis. Yoga is defined as the stilling of these vṛttis, suggesting that citta is the inner field where thoughts, emotions, memories, and even the experience of sleep appear as changing patterns. When these patterns are active, the seer (puruṣa) becomes identified with them, as if consciousness were no more than the current mental state. When they are quieted, citta can become like a transparent crystal, capable of clearly reflecting the object, the knower, or the process of knowing without distortion.

Citta is also described as that which is “seen,” an object for puruṣa rather than the ultimate subject itself. It receives impressions through the senses, processes and interprets them, and stores the resulting traces as saṃskāras and habit patterns that shape future experience. In this way, citta serves as the intermediary between pure consciousness and the world of experience, appearing conscious only because it is illuminated by puruṣa. The path of yoga, as outlined by Patañjali, is the systematic training and purification of this mind-field so that its restless movements subside and its reflective capacity can reveal the distinction between changing citta and the ever-present light of awareness.