The four modes of liberation. In Tibetan, the Drolwa (liberations) Zhee (four):

CHERDROL – Liberation through bare attention.
Liberation by way of recognizing thoughts.
“Like meeting a person whom we have met before.”

SHARDROL – Liberation as soon as it arises.
Thoughts liberate themselves as soon as they arise.
Thoughts are immediately carried along by their own momentum of arising into the natural state and liberated.
“Like a snake unknotting itself from it’s coils.”
“Like drawing on the surface of water, the picture disintegrates as soon as it is drawn.”

RANGDROL – Self-liberation.
Liberation is automatic, spontaneous, effortless, instantaneous.
Thoughts arise into their immediate and spontaneous liberation; their very arising is their liberating.
“Like a thief entering an empty house and finding there is nothing to steal.”

YAYDROL – Primordial Liberation.
Rigpa itself, which has never been otherwise than totally liberated from the very beginning.