大方廣圓覺修多羅了義經略疏 2.50

2.50

The four modes of birth, such as egg-born, are differences in receiving birth. Therefore, the Yogācāra-bhūmi explains sentient beings as: 'Volitional karma is the cause; shell, womb, moisture, and defilement are the conditions; the initial arising of the five aggregates is birth.' If matching the four births to the six destinies: devas and hells are transformationally born; pretas encompass womb and transformation—meaning ghost-children and earth-dwelling rākṣasas are womb-born, while the rest are transformationally born; humans and animals each have all four. Humans possess all four: Mother Viśākhā gave birth to thirty-two sons from eggs; ordinary people are womb-born; Āmrapālī is moisture-born; beings at the beginning of the kalpa were transformationally born. Animals possess all four: garuḍas and nāgas, other beasts being womb-born and other birds being egg-born. However, those clinging to earth or flying in the sky, in water or on land, microscopic crawling insects, whether egg-, womb-, moisture-, or transformationally born, cannot be fully classified into categories. 'All rectify their nature and life through sexual desire': sexual desire means addiction, defilement, and passionate attachment. Whenever there is emotional defilement, it is collectively termed sexual desire; even transformational birth depends on karmic defilement. Taking only the coarse and subtle within the desire realm, the Abhidharmakośa says: 'The six heavens of the desire realm indulge in sex by embracing, holding hands, laughing, and gazing.' The humans of the four continents are identical to the realm of the Four Heavenly Kings. As for the other diverse species with forms born from eggs, moisture, or wombs, their mental defilement and transmission of energy are hard to analyze exhaustively; receiving their nature and taking life is invariably due to this. Since nature and life depend on sex, and sex in turn depends on affection, it says 'affection is the root.'