法華義疏 10.169

10.169

過去有二種：一者無始，二者有始。約凡夫二乘及菩薩不見其初故言無始，而非無初證法身，是故有始。今言無後者，非但凡夫二乘及菩薩不知其後，又一證法身則畢竟無滅，具此二義故稱倍也。

The past has two aspects: first, beginningless; second, having a beginning. In terms of ordinary persons, the two vehicles, and bodhisattvas not seeing its beginning, it is called beginningless; yet it is not that there was no initial realization of the dharmakāya, and so it has a beginning. Now saying "without end": not only do ordinary persons, the two vehicles, and bodhisattvas not know its end, but once the dharmakāya is realized, it is ultimately without extinction. Possessing these two meanings, it is called "twice."