Cause (2)
Hetu Sutta  (SN 22:19)

Near Sāvatthī. There the Blessed One addressed the monks, “Monks, form is stressful. Whatever cause & condition there is for the arising of form, that, too, is stressful. Being brought into play by what is stressful, how could form be easeful?

“Feeling is stressful…

“Perception is stressful…

“Fabrications are stressful…

“Consciousness is stressful. Whatever cause & condition there is for the arising of consciousness, that, too, is stressful. Being brought into play by what is stressful, how could consciousness be easeful?

“Seeing thus, the instructed disciple of the noble ones grows disenchanted with form, disenchanted with feeling, disenchanted with perception, disenchanted with fabrications, disenchanted with consciousness. Disenchanted, he becomes dispassionate. Through dispassion, he is released. With release, there is the knowledge, ‘Released.’ He discerns that ‘Birth is ended, the holy life fulfilled, the task done. There is nothing further for this world.’”

See also: MN 146; SN 22:60