妙法蓮華經玄義 6.202

6.202

若約諸趣，欲出地獄入畜，欲出畜入鬼，欲出鬼入脩羅，欲出脩羅入人道，皆傳傳有因。因成業轉，此例可知（云云）。

If explained with reference to the various destinies: wishing to leave hell and enter the animals, wishing to leave animals and enter the ghosts, wishing to leave ghosts and enter the asuras, and wishing to leave asuras and enter the human destiny, all sequentially have their causes. When causes are completed, karma turns; this principle can be understood by analogy (and so on).