Philosophical Works · Chapter
CXCV explained
This chapter discusses the sense of sight, explaining that the optic nerves' extremities (the retina) are moved only by globules of the second element, not by air or terrestrial objects, thereby producing the sensation of light and colors,
What happens
This chapter discusses the sense of sight, explaining that the optic nerves' extremities (the retina) are moved only by globules of the second element, not by air or terrestrial objects, thereby producing the sensation of light and colors, as previously detailed in Descartes' Dioptrics and treatise on Meteors.
Themes in this chapter
Reason and Method
Descartes applies his mechanistic method to explain the sense of sight, relying on clear and distinct principles of physics.
Characters to notice
- Narrator
The narrator explains the mechanism of sight and references Descartes' earlier works.
- René Descartes
The author of the Dioptrics and treatise on Meteors, whose theories on light and color are referenced.
Key passages
“Finally, the extremities of the optic nerves, composing the coat in the eyes called the retina, are not moved by the air nor by any terrestrial object, but only by the globules of the second element, whence we have the sense of light and colours: as I have already at sufficient length explained in the Dioptrics and treatise of Meteors.”
The retina, which is the inner layer of the eye formed by the ends of the optic nerves, is stimulated solely by tiny particles of the second element, not by air or earthly objects; this stimulation gives rise to our perception of light and color, as I have thoroughly described in my earlier works on optics and meteors.
This passage summarizes Descartes' mechanistic theory of vision, emphasizing the exclusive role of subtle matter in sensory perception.