首楞嚴義疏注經 4.107

4.107

"Seed" refers to that which has already been moistened by love and grasping, which is the seed of distinct origins; hence it says "flowing love becomes the seed." "Womb" specifically concerns the very time when a single thought of the active conscious mind arises. Yet seed means that both thought and love serve as seed, and womb means that both thought and love serve as womb; the sūtra text abbreviates, and therefore mentions one for each. The emotions and thoughts of the parents and the child at the three places mutually intermingle and encounter each other, giving rise to and drawing in the shared karma of realms and destinies, causing them to return to a single place and coalesce into an embryonic womb; hence it says "intercourse and confluence bring forth occurrence, attracting shared karma." One's own karma is the cause, and the emotions and thoughts of the three places are the conditions. Kalala is called coagulated slipperiness. Arbuda is called a blister—these are the first two [periods of] seven days in the womb. If reaching the third [period of] seven days, womb-birth and egg-birth are differentiated; hence it is stated regarding the first two stages before differentiation.