Visuddhimagga XV-9

Tāvatvatoti tāvabhāvato. Idaṃ vuttaṃ hoti – cakkhādayopi hi dhammā eva, evaṃ sati dhammāyatanamicceva avatvā kasmā dvādasāyatanānīti vuttānīti ce.

（三）「以限量」，即是说以那样的数量。眼等亦即是法。那末，为什么不说眼等为法处，却说为十二处呢？

Ñ(XV,9): 3. As to just so much: as just so many. What is meant is this: The eye, etc., are mental data too; that being so, why is 'twelve bases' said instead of simply 'mental-data base'?

Chaviññāṇakāyuppattidvārārammaṇavavatthānato idha channaṃ viññāṇakāyānaṃ dvārabhāvena ārammaṇabhāvena ca vavatthānato ayametesaṃ bhedo hotīti dvādasa vuttāni,

因为依据确定[PTS 483]六识身生起的门及所缘之故，即由于确定这六识身的门及所缘的差别故说为十二。

Ñ: It is for the sake of defining door-cum-object for the arising of the six consciousness groups. And here they are stated as twelve since this is how they are classed when so defined. [483]