首楞嚴義疏注經 4.79

4.79

The first two lines point to the preceding two natures as the cause of generating fire. Internally, arising and ceasing do not cease, and solid clinging is not abandoned; externally, motion does not rest, and rigid hardness is difficult to destroy; mutually rubbing against each other, fire is produced—just as in the method of producing fire with a drill and wood, where one is solid and the other in motion. Fire can melt and disperse, bringing all things to maturity; hence it is said to be "the nature of transformation."