Descartes would not trust the truth of the thoughts which his mind gave him. Yet he was quite willing incautiously to trust the mind itself! For what is this everyday mind which he took to be his "I" but a persisting series of recurring thoughts? What is this "I" but an entity created by habit and convenience out of their totality?
-- Notebooks Category 8: The Ego > Chapter 2: I-thought > # 42