首楞嚴義疏注經 1.308

1.308

若謂不論前後，但是見暗便即內者，汝處幽室無三光時，比室黯然，應是汝內，以同暗故，焦腑即內也。應立量云：汝處幽室應汝焦腑，以是暗故，同汝見暗。

If you say that regardless of front or back, merely seeing darkness is immediately the inside, then when you dwell in a dark room without the three lights, that dark room should be your inside, because it is equally dark; the internal organs are precisely the inside. A syllogism should be formulated: your dwelling in a dark room should be your internal organs, because it is dark, just like the darkness you see.