瑜伽論記 7.428

7.428

第四明六界觀者，尋思六事，尋思去來今世，六界為緣，得入母胎等者，謂捨中有觀待生有四大空識依託不淨得入母胎，復由宿世諸業煩惱及自名言種子以為因緣等，盡解觀待義。

Fourth, explaining the contemplation of the six elements: "investigating the six matters, investigating past, future, and present, taking the six elements as conditions, obtaining entry into the mother's womb, etc." This means abandoning the intermediate existence and, in dependence on the four great elements, space, and consciousness of the birth existence, relying upon impurity to enter the mother's womb; furthermore, taking the karma and afflictions of past lives and one's own seeds of conventional expression as causes and conditions, etc., completely understanding the meaning of dependence.