'things to be realized'.

Recollection of former states of existence is to be realized through remembrance (abhiññā 4).

The vanishing and reappearing of beings is to be realized through the divine eye (abhiññā 5).

The 8 deliverances (vimokkha) are to be realized through the mental group (kāya, here feeling, perception, mental formations; s. kāya).

The extinction of cankers is to be realized through insight (vipassanā).