# XII explained — Philosophical Works > Chapter companion for Philosophical Works by René Descartes. ## What happens Descartes explains why not everyone arrives at the same clear knowledge of the mind: because they have not philosophized in order and have failed to distinguish the mind from the body. They mistakenly attribute the faculty of perception to the body, which they see and touch, and thus fail to apprehend the nature of the mind distinctly. ## Themes in this chapter ### Mind-Body Dualism The chapter emphasizes the critical distinction between mind and body, noting that those who conflate them fail to achieve metaphysical certainty. ### Reason and Method Descartes stresses the importance of philosophizing in order to properly distinguish the mind from the body. ## Character check-ins ### Narrator The narrator explains the common error of conflating mind and body. ### René Descartes Descartes is the implied authorial voice presenting the argument. ## Key lines > Those who have not philosophized in order have had other opinions on this subject, because they never distinguished with sufficient care the mind from the body. People who have not followed a proper philosophical method hold different views because they have not carefully separated the mind from the body. _Descartes attributes confusion about the self to a lack of methodical distinction between mind and body._ > they rather meant their bodies which they saw with their eyes, touched with their hands, and to which they erroneously attributed the faculty of perception Instead, they meant their bodies—which they could see and touch—and mistakenly thought the body itself could perceive. _The common error is to identify the self with the physical body and to wrongly assign perception to it._ ## Links - HTML: https://www.betterreads.online/discover/philosophical_works_se/chapters/xii - Book: https://www.betterreads.online/discover/philosophical_works_se - All chapters: https://www.betterreads.online/discover/philosophical_works_se/chapters