法界次第初門 2.75

2.75

次十一切處而辯十四變化者，上所明觀禪正體雖備，猶未辯其功用。今欲學六通之用，必須先修變化心也。通言變化者，能使無而欻有、有而欻無，故名為變化也。

The reason why the fourteen transformations are explained after the ten kṛtsnāyatanas is that although the primary essence of contemplative dhyāna explained above is fully present, its function has not yet been elucidated. Now, wishing to learn the functions of the six superknowledges, one must first cultivate the mind of transformation. 'Transformation' in general means being able to make what is non-existent suddenly exist, and what exists suddenly non-existent; hence it is called transformation.