大方廣圓覺修多羅了義經略疏 2.50

2.50

卵等四生則受生差別，故《瑜伽》釋眾生云：「思業為因，殼、胎、濕、染為緣，五蘊初起為生。」若以四生配六道者，天及地獄化生；鬼通胎、化，謂鬼子及地行羅剎是胎，餘皆化生；人畜各四，人具四者，毘舍佉母卵生三十二子，胎則常人，濕則柰女，化為劫初；畜具四者，金翅及龍，餘獸皆胎，餘鳥皆卵。然著地飛空、若水若陸、微細蠢動，或卵胎、或濕化，不可具分品類。皆因淫欲正性命者，淫謂耽染愛著，但是情染，總得名淫，縱使化生亦依業染。但約欲界輕重者，《俱舍》云：「六受欲交抱，執手笑視淫。」四洲之人同四王界，餘諸異類卵濕胎形，心染氣傳難具分析，受性稟命莫不由之。既性命由淫，淫復由愛，故云愛為根本。

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.'