妙法蓮華經文句 1.69

1.69

後劫立，本相還現，得神通人，知昔名以名今耳。例如先劫姓瞿曇，將本姓以姓今也。

When a later kalpa is established, the original appearance manifests again; those endowed with supernormal powers know the ancient name and use it to name the present one. This is just as in a previous kalpa someone was of the Gautama clan, and the original clan name is used to name the present one.