p. 232
अयं मानस्य विषयो ह्यसौ मौनस्य तद्विदुः ॥
In plain words
This one is the range of māna, what can be measured; that one is the range of mauna, silence — so those who know it say.
Close to the Sanskrit
This indeed is the domain of māna; that is the domain of mauna — thus they know it.