首楞嚴義疏注經 3.177

3.177

This refutes joint arising. If the sense faculty and the objective realm unite to produce the intermediate realm, this intermediate realm of consciousness would differ between knowing and not knowing; hence it says 'the middle is separated'. If they form distinct parts, then half of this intermediate realm of consciousness would unite with the faculty and half would unite with the realm; hence it says 'they doubly unite'. If a double union were formed, there would be the fault of mixture and confusion, because knowing and not knowing would share a single realm, so the meaning of 'realm' would be invalidated. Alternatively, 'separated' (li) has the sense of opening apart, or resembles 'nonexistent'.