摩訶止觀 2.71

2.71

謂觀未見色、欲見、見、見已四運心，種種推求，不得所起之心，亦不得能觀之心，不內外，無去來，寂無生滅（其一）。

That is, contemplating the mind in the four phases of movement—not yet seeing form, wishing to see, seeing, and having seen: investigating through various methods, one cannot grasp the mind that arose, nor can one grasp the mind that can contemplate; it is neither internal nor external, has no coming or going, and is quiescent without arising or ceasing (first).