金剛經纂要刊定記 4.21

4.21

稟命之始名曰受生，即初起之時也。卵等四異故云差別。謂：卵㲉中生，胎藏中生，依濕而生，化忽然生，故不同也。然三界眾生不出五道，以四攝五亦得具足。故疏次云「天獄等化生」，斯則從狹之寬，明也。

The beginning of receiving life is called "taking birth," which is the time of initial arising. The four differences such as egg are why it says "distinctions." Namely: born from within an eggshell, born from within a womb, born dependent on moisture, and suddenly born by transformation; therefore they are not the same. However, sentient beings of the three realms do not go beyond the five destinies, and using the four [births] to subsume the five is also complete. Therefore the commentary next says "transformationally born in the heavens and hells, etc.," which makes clear proceeding from the narrower to the broader.