तत्त्वमस्यादिवाक्यं च तादात्म्यप्रतिपादने ।लक्ष्यौ तत्त्वंपदार्थौ द्वावुपादाय प्रवर्तते ॥ ४२ ॥
In plain words
To establish the direct identity between individual and absolute, sentences like 'That thou art' operate by taking up the two underlying, implied realities of those terms.
Close to the Sanskrit
And the sentence 'tat tvam asi' and others, in establishing identity, proceeds by taking up two indicated meanings of the terms 'tat' and 'tvam'.