大方廣佛華嚴經隨疏演義鈔 9.22

9.22

疏「一理齊平故說生界佛界不增不減」者，第五生佛不增不減別。此但義異，名乃不殊。謂法性既同，設令一切眾生一時成佛，生界不減、佛界不增，以生佛界既是法性，不可以法性增法性。喻如東方虛空是眾生，西方虛空是佛，不可以東方虛空添西方虛空，令東減西增，故不增不減。《大般若》等經皆約一性平等而說。

Regarding the Commentary's statement "because the single principle is completely equal, it is said that the realm of sentient beings and the realm of buddhas neither increase nor decrease": this is the fifth, the distinction that sentient beings and buddhas neither increase nor decrease. Here only the meaning is different, while the names do not differ. That is to say, since the dharmatā is identical, even if all sentient beings were to simultaneously become buddhas, the realm of sentient beings would not decrease and the realm of buddhas would not increase. Since the realms of sentient beings and buddhas are dharmatā, dharmatā cannot be added to dharmatā. For example, just as space in the east is sentient beings and space in the west is buddhas, one cannot add space in the east to space in the west to make the east decrease and the west increase; hence there is neither increase nor decrease. Sūtras such as the Mahāprajñāpāramitā all speak according to the equality of the single nature.