摩訶止觀 9.36

9.36

若欲去之，但呵覺、觀；初禪謝已，即發中間單定，亦名「轉寂心」，亦名「退禪地」，亦名「篾屑心」。於此單靜心中，既失下，未發上，若生憂悔，此心亦失。若不悔者，內淨即發，無復八觸受納分別，故名「一識定」；混四大色成一淨色。照心轉淨，與喜俱發，無魔邪相，以非邊境故。喜已生樂，樂謝入一心。

If one wishes to remove them, one simply reproaches applied and sustained thought; when the first dhyāna has subsided, the solitary concentration of the intermediate stage immediately manifests, also called the 'mind of turning toward quiescence,' also called the 'ground of retreating dhyāna,' and also called the 'trifling mind.' Within this solitary, quiet mind, having already lost what is below and not yet manifested what is above, if one gives rise to sorrow and regret, this mind is also lost. If one does not regret, inner purity immediately manifests, free from the reception and discrimination of the eight touches; hence it is called the 'concentration of single consciousness,' fusing the matter of the four great elements into a single pure matter. The illuminating mind becomes increasingly pure, manifesting together with joy, free of demonic or improper marks because it is not a border realm. After joy, bliss arises; when bliss subsides, one enters one-pointedness of mind.