Treasury of Optics

The arguments of the triple mode of vision—direct, reflected, and refracted—which are the subjects of optical study. The author here defines the three pillars of classical optics: direct (light in a straight line), reflected (light bouncing off mirrors), and refracted (light bending through glass or water).

A detailed woodcut illustration depicting various optical and natural phenomena. In the upper left, a rainbow A natural demonstration of both refraction and reflection. arches across the sky. In the upper right, a personified sun radiates beams of light over a coastal landscape. The middle ground shows a fortified city with domes and towers bordering a body of water with several sailing ships. On the left side of the image, a long, straight staircase or ramp ascends a mountain. In the foreground, a nude man stands gesturing towards a seated man who holds a circular optical instrument, likely a mirror. To the far left, a group of animals, including a bear and lions, are gathered. The composition allegorically represents the three modes of vision: direct light, reflection, and refraction.

Optics (original: optica): The scientific study of light and its interactions with matter.
Vision (original: uisus): The process of seeing, which early scholars debated as either light entering the eye or rays emitting from it.
Direct vision (original: directi): Light traveling in a straight path from a source to the eye.
Reflected vision (original: reflexi): The study of light bouncing off surfaces, known as catoptrics.
Refracted vision (original: refracti): The study of light bending as it passes through different materials, known as dioptrics.
Arguments (original: argumenta): The central themes or proofs presented in the following text.