# CXCIX explained — Philosophical Works

> Chapter companion for Philosophical Works by René Descartes.

## What happens

Descartes asserts that no natural phenomenon has been omitted from his treatise, as all phenomena perceived by the senses reduce to motion, magnitude, figure, and the dispositions of objects, with secondary qualities like light, color, and taste being merely subjective perceptions of these primary attributes.

## Themes in this chapter

### Reason and Method

Descartes demonstrates his method of reducing all sensory phenomena to primary qualities (magnitude, figure, motion) and explaining them through clear and distinct principles.

### Mind-Body Dualism

The distinction between subjective sensory qualities (perceived by the mind) and objective physical properties (extension, motion) reinforces the dualism between mind and body.

## Character check-ins

### Narrator

The narrator (Descartes) summarizes the completeness of his explanation of natural phenomena.

## Key lines

> there is no phenomenon of nature whose explanation has been omitted in this treatise; for beyond what is perceived by the senses, there is nothing that can be considered a phenomenon of nature.

Every natural phenomenon has been accounted for in this work, since only what the senses perceive counts as a natural phenomenon.

_Descartes claims completeness for his physical theory by equating natural phenomena with sensory perceptions._

> we perceive nothing out of us by our senses except light, colours, smells, tastes, sounds, and the tactile qualities; and these I have recently shown to be nothing more, at least so far as they are known to us, than certain dispositions of the objects, consisting in magnitude, figure, and motion.

Our senses only give us light, colors, smells, tastes, sounds, and tactile sensations, which I have shown are merely arrangements of the objects' size, shape, and motion.

_Descartes reduces all sensory qualities to primary physical properties, a key tenet of his mechanistic worldview._

## Links

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