त्वमर्थमेवं निश्चित्य तदर्थं चिन्तयेत्पुनः ।अतद्व्यावृत्तिरूपेण साक्षाद्विधिमुखेन च ॥ २८ ॥
In plain words
Once you have settled what 'you' actually means, turn next to what 'That' means. Come at it both ways: by ruling out everything that is not That, and directly, by affirming what It is.
Close to the Sanskrit
Having thus ascertained the meaning of 'you', one should then reflect upon the meaning of 'That' — by way of the exclusion of what is not That, and directly, by way of positive affirmation.