Yoga is the cessation of the fluctuations of the mind.

This is the defining sutra. In four words, Patañjali condenses the entire system:

• Yoga — Union, integration
• Citta — The mind in its totality (mind, intellect, memory, ego)
• Vṛtti — Fluctuations, waves, modifications
• Nirodha — Cessation, restraint, control

The mind in its ordinary state is in constant movement: thoughts, memories, projections, reactions. Yoga seeks to quiet this movement, not to suppress it violently but to allow it to settle naturally.

When fluctuations cease, clarity arises.