The fifteenth chapter of the Catukka Nipāta of the Aṅguttaranikāya.
It consists of ten suttas on such subjects as
- the four kinds of radiance — the sun, moon, fire, and wisdom,
- the four due seasons,
- the four vices and virtues of speech — lying, slander, abuse, idle chatter, and their opposites,
- the four essences (sāra) — morality, concentration, wisdom, and liberation,