Kaivalya-pâdaï – Freedom
In book IV Patañjali writes on the cessastion of samsara and therefore freedom from rebirth. This is the end-point of Rāja Yoga.
Here are some excerpts from an excellent book by Chip Hartranft
The Eternal Now
Yoga sūtras of Patañjali IV Kaivalya-pâdaï
Dreamyoga 