[577] Therein, what is right concentration (sammāsamādhi)?
Here a bhikkhu, quite secluded from sensual pleasures (kāma), secluded from unwholesome phenomena (akusalā dhammā), enters and dwells in the first jhāna, which is accompanied by applied thought (vitakka) and sustained thought (vicāra), with rapture (pīti) and pleasure (sukha) born of seclusion. With the subsiding of applied thought and sustained thought, he enters and dwells in the second jhāna, which has internal confidence (sampasādana) and unification of mind (cetaso ekodibhāva), is without applied thought and without sustained thought, and has rapture and pleasure born of concentration (samādhi). With the fading away of rapture, he dwells equanimous (upekkhaka), and, mindful (sato) and clearly comprehending (sampajāno), he experiences pleasure with the body; he enters and dwells in the third jhāna, of which the noble ones declare: "He is equanimous, mindful, one who dwells in pleasure." With the abandoning of pleasure and the abandoning of pain (dukkha), and with the previous passing away of joy (somanassa) and grief (domanassa), he enters and dwells in the fourth jhāna, which is neither painful nor pleasant (adukkhamasukha) and has purity of mindfulness due to equanimity. This is called right concentration.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.