因明入正理論疏 2.153

2.153

非勤勇宗，電晃等并虛空等皆是同品，並非勤勵勇銳無間所發顯故。無常之因，電有空無，故是同品一分轉也。

For the proposition of not being produced by deliberate effort, flashing lightning and the like, as well as space and the like, are all the homologous class, because they are all not manifested immediately through vigorous, diligent effort. For the reason of non-eternality, it exists in lightning but is absent in space; therefore, it is occurring in part of the homologous class.