Visuddhimagga XXI-122

Yasmā panesa aniccānupassanāya saṅkhārānaṃ ghanavinibbhogaṃ katvā niccanimittadhuvanimittasassatanimittāni pajahanto āgato, tasmā animitto. Dukkhānupassanāya pana sukhasaññaṃ pahāya paṇidhiṃ patthanaṃ sukkhāpetvā āgatattā appaṇihito. Anattānupassanāya attasattapuggalasaññaṃ pahāya saṅkhārānaṃ suññato diṭṭhattā suññatoti idaṃ paccanīkato nāmaṃ nāma.

（二）因为这（道）是由于无常随观除了诸行的坚厚（想），及舍断常相、恒相、常恒相而来，故为无相。由于苦随观舍断了乐想，干竭了愿与希求而来，故为无愿。由于无我随观舍断了我、有情、补特伽罗想，见诸行为（我等之）空，故为空。这是以反对者而得（道之）名。

Ñ(XXI,122): 2. When this path is arrived at with the abandoning of the signs of permanence, lastingness, and eternalness, by effecting the resolution of the compact in formations by means of the contemplation of impermanence, it is then called signless. When it is arrived at with the drying up of desire and longing, by abandoning perception of pleasure by means of the contemplation of pain, it is then called desireless. When formations are seen as void by abandoning perception of self, of a living being, of a person, by means of the contemplation of not-self, it is then called void. This is its name according to what it opposes.