1"Bhikkhus, just as a stick thrown up into the air falls now on its bottom, now on its top,

so too as beings roam and wander on, hindered by ignorance and fettered by craving, now they go from this world to the other world, now they come from the other world to this world.[n.394] Cp. SN15.9, which says the stick might also fall on its middle.

For what reason? Because they have not seen the Four Noble Truths. What four?

The noble truth of suffering,
the noble truth of the origin of suffering,
the noble truth of the cessation of suffering,
the noble truth of the way leading to the cessation of suffering. sn.v.440

2"Therefore, bhikkhus, an exertion should be made to understand: ‘This is suffering.’[n.376] Tasmātiha bhikkhave idaṁ dukkhan ti yogo karaṇīyo. Spk: Since a concentrated bhikkhu understands the Four Noble Truths as they really are, therefore you should make an exertion to become concentrated in order to understand the four truths as they really are. And since the round of existence increases for those who do not penetrate them, but stops increasing from the time they are penetrated, therefore you should make an exertion to understand them, thinking, "Let the round not increase for us."
An exertion should be made to understand: ‘This is the origin of suffering.’
An exertion should be made to understand: ‘This is the cessation of suffering.’
An exertion should be made to understand: ‘This is the way leading to the cessation of suffering.’"

1"Seyyathāpi, bhikkhave, daṇḍo uparivehāsaṁ khitto sakimpi mūlena nipatati, sakimpi aggena nipatati;

evameva kho, bhikkhave, avijjānīvaraṇā sattā taṇhāsaṁyojanā sandhāvantā saṁsarantā sakimpi asmā lokā paraṁ lokaṁ gacchanti, sakimpi parasmā lokā imaṁ lokaṁ āgacchanti.

Taṁ kissa hetu? Adiṭṭhattā, bhikkhave, catunnaṁ ariyasaccānaṁ. Katamesaṁ catunnaṁ?

Dukkhassa ariyasaccassa … pe … dukkhanirodhagāminiyā paṭipadāya ariyasaccassa.

2Tasmātiha, bhikkhave, ‘idaṁ dukkhan’ti yogo karaṇīyo … pe … ‘Ayaṁ dukkhanirodhagāminī paṭipadā’ti yogo karaṇīyo"ti.

Tatiyaṁ.