大般涅槃經集解 46.36

46.36

案僧亮曰：已增長最後身，是名牙生，過是則非也，牙是未生。如牙增長者，牙生未增，是名生生者也。

Sengliang notes: Having grown into the final body is called the sprout being born; beyond this, it is not; the sprout is what was not yet born. 'Like the sprout growing': the sprout is born but not yet grown; this is called 'the born being born.'