俱舍論記 27.111

27.111

「六中三種至治中際愚」者，釋第二句。六中三種獨名明者，宿住智通治前際愚，死生智通治後際愚，漏盡智通治中際愚。由智現前，令彼現在惑不起故，名治中際。餘三不爾，故不立明。又《正理》云「宿住智通憶念前際自、他苦事。死生智通觀察後際他身苦事。由此厭背生死眾苦，起漏盡通觀涅槃樂故。唯三種偏立為明。」廣如彼說。

As for "Among the six, three … cures ignorance regarding the middle period": This explains the second line. That three among the six are exclusively named clear knowledge (vidyā) is because the supernormal knowledge of past abodes cures ignorance regarding the prior period, the supernormal knowledge of death and birth cures ignorance regarding the subsequent period, and the supernormal knowledge of the destruction of outflows cures ignorance regarding the middle period. Because of the presence of knowledge, it causes those present defilements not to arise; hence it is called curing the middle period. The remaining three are not like this, and therefore are not established as clear knowledges. Furthermore, the Nyāyānusāra says: "The supernormal knowledge of past abodes recollects the sufferings of oneself and others in the prior period. The supernormal knowledge of death and birth observes the sufferings of other bodies in the subsequent period. Thereby revulsion is generated toward the manifold sufferings of saṃsāra, giving rise to the supernormal knowledge of the destruction of outflows to observe the bliss of nirvāṇa. Therefore, only these three are singled out to be established as clear knowledges." It is explained at length as stated there.