Four fruition levels of the arhat: 1) The stream-entrant, who has erased all doubts about the path. 2) The once-returner, Who will be reborn in samsara only once more. 3) The non-returner, Who will not be reborn in the human realm. 4) The arhat, how has attained liberation in nirvana.

Four dhyana stages: l) relinquishing of desires, 2) joy and one-pointedness, 3) equanimity and 4) equanimity and wakefulness.

There are nine samadhi levels, of which the ninth is the liberation experience of true emptiness by an arhat.

The three realms of existence constitute samsara, where sentient beings are subject to the cycles of birth and death. The three realms are desire, form, and formlessness.

Tathagata: one of the epithets of the Buddha, meaning 'thus come.'