摩訶止觀 2.48

2.48

初明四運者，夫心識無形，不可見，約四相分別，謂未念、欲念、念、念已。未念，名心未起；欲念，名心欲起；念，名正緣境住；念已，名緣境謝。若能了達此四，即入一相無相。

First, explaining the four movements: the mental consciousness is formless and cannot be seen, but is distinguished according to four marks: not-yet-thinking, about-to-think, thinking, and having-thought. Not-yet-thinking means the mind has not yet arisen; about-to-think means the mind is on the verge of arising; thinking means directly fixing on an object and abiding; having-thought means the conditioning of the object has ceased. If one can thoroughly comprehend these four, one enters the single mark of marklessness.