首楞嚴義疏注經 1.359

1.359

破一也。心體若一，四處咸同，一支受觸，四應俱覺。設許俱覺，失本觸處，故云無在。若覺元所觸處，一體之義豈存？

This refutes 'one.' If the mind's substance is one, the four places are all identical; when one limb receives a touch, all four should feel it. If one grants that all feel it, the original place of touch is lost; hence he says 'it has no specific location.' If it is aware only at the originally touched place, how can the meaning of 'one substance' remain?