摩訶止觀 3.205

3.205

復次，四種止觀入圓，不必併待行成入圓，不必併待開漸顯頓入圓，入則不定。所以者何？一切眾生心性正因，譬之於乳；聞了因法，名為置毒。正因不斷，如乳四微；五味雖變，四微恒在。是故毒隨四微，味味殺人。眾生心性，亦復如是。正因不壞，了因之毒，隨正奢促，處處得發。或理發，或教發，或行發，成證發。

Furthermore, for the four kinds of calming and contemplation to enter the perfect, it is not necessary to wait altogether for practice to be completed before entering the perfect, nor is it necessary to wait altogether for opening the gradual to reveal the sudden before entering the perfect; entry is indeterminate. Why is this? The mind-nature, the direct cause, of all sentient beings is likened to milk; hearing the illuminating-cause Dharma is called placing poison [in it]. The direct cause is uninterrupted, like the four subtleties of milk; although the five flavors transform, the four subtleties are ever present. Therefore, the poison follows the four subtleties, killing people in flavor after flavor. The mind-nature of sentient beings is also like this. The direct cause is not destroyed; the poison of the illuminating cause, following the slowness or quickness of the direct [cause], can burst forth everywhere. It may burst forth through principle, burst forth through teaching, burst forth through practice, or burst forth by achieving realization.