Yoga Sutras of Patanjali translated by Yogi Kalinath - Chapter 3, Verse 55
Pada 3, Sutra 55
Sattva-purusayoh Shuddhi-saamye kaivalyam
With the attainment of equality of purity between Mind and the Self, one attains Liberation.
A turbulent mind affected by its own vrittis or cogitations, perturbations and agitations is classified as an impure mind which obfuscates the effulgence of the Atman. When the Chitta Vrittis are arrested, the veil is lifted and the Self (the ‘Original Face’) is reflected upon the mirror of consciousness itself.
When this is realized as our original and true nature, one becomes Liberated while still operating in the body mind vehicles.
The purpose of Sadhana is to discipline and purify the mind in order for it to reflect the light of the Atman. The ultimate purpose of a human being (a being endowed with manas or mind) is to realize the Self (the Atman). And the ultimate realization is that there has never been any self but the Self.