妙法蓮華經玄義 6.190

6.190

畜生者，略有三種：水、陸、空。陸有三品：重者土內，不見光明；中者，山林；輕者，人所畜養。彊者伏弱，飲血噉肉，怖畏百端。《四解脫經》稱為血塗。其中眾生，先世善根，可發關宜。聖人赴對應之，得無所畏，獲冥、顯兩益，是為畜生果上清涼益也。

As for animals, there are briefly three kinds: water, land, and air. The land has three grades: the heavy dwell within the earth and do not see light; the middling are in mountains and forests; the light are kept and raised by humans. The strong subdue the weak, drinking blood and devouring flesh, with hundreds of kinds of terrifying dread. The Scripture on the Four Liberations calls it the "bloody path." If the sentient beings therein have wholesome roots from prior lives that can be stimulated when conditions are fitting, the sages respond accordingly, so that they attain fearlessness and obtain both hidden and manifest benefits. This is the benefit of cooling upon the fruit of animals.