US-P18.193ab ।US-P18.193cd ॥
In plain words
In the sentence 'You are That', the meanings of 'That' and 'asi' are already established. If recollection of the meaning of 'you' does not come to their aid, the sentence does not generate direct realization.
Close to the Sanskrit
In the sentence 'that thou art', the two words 'that' and 'asi' have known meanings. Without the assistance of recollecting the meaning of 'thou', the sentence would not produce valid knowledge.