Yoga Sutras of Patanjali: Samadhi Pada, Sutra 2

योगश्चित्तवृत्तिनिरोधः ॥ २॥

yogaś citta vṛttini rodhaḥ

 

2. Yogas meaning Yoga, citta (or chitta) means the workings of the mind, vrttini means fluctuations or changes, and rodhah means restraint. 

Lit. translation: Restraint on the modifications of the mind is Yoga. 

 

Swami Satchidananda says that the entire philosophy of Yoga can be summed up with this one sutra, and that all the following sutras are just explanations and embellishments on this one sutra. The meaning is simple, yet complex; deep, yet shallow. By watching the course of your mind, you can see that when your mind is in its natural state, that is when you are content. When a desire arises you try and fulfill it, when you have justified to yourself the task is complete, then you are back in the state of contentment.

 

Through Yoga we learn practices to restrain the "modifications of the mind" and therefore stay in the state of contentment.