। ॥
In plain words
With the mind sinking in silence, the search into one's own root is itself true enquiry into the Self. The knowing 'This am I; that is not my own nature' is an aid to true enquiry.
Word for word
With the mind sinking in silence, the search into one's own root alone is true enquiry into the Self. 'This am I; that is not my own nature': such knowing is a limb of true enquiry.