Part II by Ven. Mahasi Sayadaw
(49) Living in the exercise of four noble postures called Vihara
The Pali Commentaries have distinguished Vihara – “the Abiding” in four different kinds of the position of the body, viz: (1) Iriyapathavihara, (2) Dibbavihara, (3) Ariyavihara, and (4) Brahmavihara
(1) Iriyapathavihira means walking, standing, sitting and lying-down at times in turn as may be considered appropriate in accordance with the four characteristics of postures. This manner of deportment is naturally adopted by every Bhikkhu, individual or being.
(2) Dibbavihara – this means lofty mahaggata-jhanas, such as kasina-jhana, etc., by which one may become or lead to be reborn as an outstanding celestial being called Brahma, after his demise. Plunging in a profound trance in such jhanas or religious exercises productive of the highest spiritual advantages is called ‘dibbavihara’.
(3) Ariyavihara – that is, the four ariya-phalas or Fruition. To be mentally absorbed in the four Fruition which are the attainments of the results of the four Paths – the manner of abiding in the Fruition of the Paths by the Noble Ones (Arlyas) may be called ‘Ariyavihara’.
(4) Brahmavihara means the Four Jhanas, namely, metta-jhana, karuna-jhana, mudita-jhana, and upekkhajhana. In particular, by virtue of being faultless and of its noble qualities, it is said to be abiding or remaining in a perfect and holy state. That is the reason why in this verse, it has been expounded by the Buddha using the expression “Brahmavihara” for the word “metta”.