Descartes’ moral rules demonstrate both his distrust of the material world and his confidence in his mind’s ability to overcome it. He has near-absolute faith in his ability to control his own mind and believes that he only needs to change it to change reality. If he wants something he can’t have, he won’t struggle to get it or be miserable about not having it. Instead, he’ll just decide not to want it. Descartes’ resolution to become a spectator rather than an actor in the events of the world around him amounts almost to a renunciation of his physical existence. Long after Descartes, scientific study was governed by the ideal of detached observation advanced by Descartes.
Part Four of Discourse is a precursor to his later work, Meditations on First Philosophy, and the major ideas he provides here—that the self exists because it thinks and that God exists because the self is imperfect and there must be a source for the idea of perfection outside the self—are mere sketches of the detailed explanation he provides in Meditations.