瑜伽師地論略纂 2.121

2.121

That the lower four heavens take [spouses] while the upper two heavens do not is because, having attained superior fruit, they do not give rise to guarding or grasping things as their own. Furthermore, those two heavens are able to manifest as men and women to engage in sexual practice; hence they have no separate taking [of spouses]. As the *Kośa* says: Since the continent of Uttarakuru has no taking [of spouses], how do they recognize their parents and relatives? When they go toward the trees about to engage in the act, if the branches hang down and conceal them, they engage in the act; if the branches do not hang down, they know they are parents or relatives, and both return in shame. There is also an objection: Since the upper two heavens have no taking [of spouses], how can they have the courses of action of taking what is not given and sexual misconduct? Answer: There are those who have karmic fruits regarding manifested objects without taking [them as personal property]; hence the two courses of action exist. Or they simply do not have these, so what fault would there be? Among the three enjoyments of the realms, the fifth section is concluded.