OK, let's try to make it more esoteric.) Do you recall the famous picture of Escher -
http://en.wikipedia.org/wiki/Drawing_HandsThis is an artistic impression of how "body and mind" works, and this notion is as ancient as Vedas, but it does not happen to be expressed in such clever graphical form. Instead, it has been expressed in verbal form, in short snippets across Upanishads and, perhaps, Vedas.
This artistic impression also captures fundamental concepts of feed-back loops and recursion, which could explain lots of Nature's phenomena, from weather to circuits in your iPhone.
"Self-awareness" is just another name for recursion - like "to focus your attention on the contents/state of your consciousness" which could be verbally expressed as "that third eye which is looking inside one's own skull".
Btw, you cannot draw that on a tanka, so ancient Indian and then Tibetan artists render it as a eye in the forehead "looking outside", which, of course, should not be interpreted literally, like so many do.)
Technically, these two hands depicts so-called Mutual Recursion where two "processes" are "feeding" each other. This is a crude "high-level" model (a body-mind mutual recursion) of what happened in Yoga.
In your quote it has been stated that you should "calm your mind and remove all distractions first" because they are obstacles to Yoga, and then, that "Yoga is that state of unity (within yourself and with the Whole) without any impurities". So, where shall we start? The answer is - looking at these two hands - it doesn't matter. It is a mutual recursion.
Extend it with notion of multiple agencies (processes) so it will be n-process mutual recursion, to complex to be grasped by mind at once, like this clever but naive picture.
One side note. You might think that you are having a conversation with someone with superficial understanding, based on some popular memes, but no, I am cultural guide and mountaineering instructor in Himalaya regions and North India for years.)