[118] Therein, which is the air element (vāyodhātu)?
The air element is twofold: there is the internal and there is the external.
Therein, which is the internal air element? That which is internal, belonging to oneself — air, airiness, the rigidity of form — internal, clung-to (upādinna); namely: up-going winds, down-going winds, winds in the belly, winds in the bowels, winds coursing through all the limbs, knife-like winds (satthakavātā), razor-like winds (khurakavātā), uppalaka winds (uppalakavātā), in-breathing and out-breathing; or whatever else there is that is internal, belonging to oneself — air, airiness, the rigidity of form — internal, clung-to: this is called the internal air element.
Therein, which is the external air element? That which is external — air, airiness, the rigidity of form — outside, not clung-to (anupādinna); namely: east winds, west winds, north winds, south winds, dusty winds, dustless winds, cold winds, hot winds, gentle winds, strong winds, black winds, verambha winds, winds from wings, winds from supaṇṇas, winds from a palm-leaf fan, winds from a fan; or whatever else there is that is external — air, airiness, the rigidity of form — outside, not clung-to: this is called the external air element.
That which is the internal air element and that which is the external air element — having gathered them together and combined them into one, this is called the air element.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.