US-P18.065ab ।US-P18.065cd ॥
In plain words
Take the intellect's doing and lay it on the Self, and you say "he knows" — and so the Self gets called the knower. Take consciousness and lay it on the intellect, and here the intellect gets called the one who knows.
Close to the Sanskrit
Having superimposed the agency of the intellect [upon the Self], 'he knows' — thus he is called a knower. Likewise, having superimposed consciousness [upon the intellect], knowership of the intellect is here spoken of.