摩訶止觀 3.115

3.115

種種憶想是第一義者，想是慧數，僻故成心倒、見倒等；若遇知識，正此想慧，即成三不倒。佛欲正其此慧，故說三諦，即第一義也。

Regarding "various kinds of recollection and thought" being the ultimate truth: thought is a caitta belonging to wisdom, which, when warped, becomes inversions of mind, inversions of view, and so forth. If one encounters a good friend who rectifies this thought and wisdom, it then becomes the three non-inversions. Because the Buddha wished to rectify this wisdom of theirs, he taught the three truths, which is the ultimate truth.