Stilling the thought waves of the mind
The Yoga Sūtras of Patañjali define the essence of yoga as follows:
योगश्चित्तवृत्तिनिरोध || Sūtra 1.2 ||
English transl: Yoga is the restriction (Nirodha) of the fluctuations (Vritti) of consciousness (Chitta).
लोकाः समस्ताः सुखिनो भवन्तु
Lokāḥ samastāḥ sukhino bhavantu
“May all beings everywhere be happy and free, and may the thoughts, words, and actions of my own life contribute in some way to that happiness and to that freedom for all.”