1.1 atha yoga anushasanam

Here and now the teachings of yoga can begin.

1.2 yogash chitta vritti nirodhah

Yoga is the stilling of the fluctuations of the mind.

1.3 tada drashtuh svarupe avasthanam

Then the Seer abides in Itself, resting in its own True Nature, which is called Self-realization.

1.4 vritti sarupyam itaratra

At other times, when one is not in Self-realization, the Seer appears to take on the form of the modifications of the mind field, taking on the identity of those thought patterns.

Translation and Transliteration mostly pulled from Swamij.com.