# LIII explained — Philosophical Works

> Chapter companion for Philosophical Works by René Descartes.

## What happens

Descartes explains that each substance has one principal attribute that constitutes its nature: thought for the mind and extension for the body. All other properties are merely modes of these primary attributes.

## Themes in this chapter

### Mind-Body Dualism

The chapter explicitly distinguishes mind (thinking substance) from body (extended substance) by their principal attributes.

## Character check-ins

### Narrator

The narrator presents the argument that each substance has a principal attribute.

## Key lines

> That of every substance there is one principal attribute, as thinking of the mind, extension of the body.

Every substance has a single defining attribute: thought for the mind, extension for the body.

_This establishes the core dualist principle._

> Thus, extension in length, breadth, and depth, constitutes the nature of corporeal substance; and thought the nature of thinking substance.

The essence of physical substance is extension in three dimensions, while the essence of mental substance is thought.

_Clarifies the distinct essences of mind and body._

## Links

- HTML: https://www.betterreads.online/discover/philosophical_works_se/chapters/liii
- Book: https://www.betterreads.online/discover/philosophical_works_se
- All chapters: https://www.betterreads.online/discover/philosophical_works_se/chapters