Lecture Notes on the Sūtra of the Collection of the Father and Son (38)

What is the external fire element?

Original text: 云何外火界。谓不执受。温热相生。若复有人。于旷野中。寻求火缘。或以蒿艾。或牛粪屑。或兜罗绵。引火生已。或烧草木。山林聚落。及余方处。皆为所烧。

Explanation: What is the external fire element? It is the mark of warmth and heat that is not singly upheld by one's own tathāgatagarbha, but is the mark of warmth and heat jointly upheld by the tathāgatagarbhas of all sentient beings sharing common karma — this is the external fire element. If someone in the wilderness seeks external conditions for making fire — using mugwort or artemisia, or cow dung shavings, or cotton (tūla) — and kindles the fire with a convex lens or a fire-starting device, once the fire is brought forth, it can burn grass and trees, mountains, forests, villages and settlements, and everything touchable in the surrounding areas can all be burned by the great fire.