plato.png

Marble bust of Plato — Roman copy after a Greek original by Silanion, Musei Capitolini MC1377. Photograph by Marie-Lan Nguyen (Wikimedia Commons user Jastrow), released into the public domain.

Source: File:Plato Silanion Musei Capitolini MC1377.png, Wikimedia Commons. Downloaded at 1280 px width; plato__line.png is the print line-art version, generated with img2line --backend neural --style contour_style.

descartes.png

Portrait of René Descartes, after Frans Hals (17th century), Musée du Louvre. The painting is public domain by age. The exact scan this file came from was not recorded when it was added to the repository.

descartes__line.png is the print line-art version, same generator as above.

brain-in-a-vat.png

The standard brain-in-a-vat diagram, a variant of the illustration by Wikimedia Commons user was a bee (whose language versions are released as public domain or CC0; the vector brain derives from Image:Central nervous system.svg by grm_wnr).

Provenance not fully verified. This file predates the current work and its dimensions (1280×1033) do not match the English Commons version (File:Brain in a vat (en).png, 819×872), so it is a different rendering or variant and the exact source file could not be identified. Worth confirming before the next public deploy — if it cannot be matched, the Commons original is a drop-in public-domain replacement.

brain-in-a-vat__line.png is the print version: the same diagram thresholded to pure black-on-white (magick … -colorspace gray -threshold 55%), since the source is already line work and an edge detector would only degrade it.

Not used, deliberately

Stills from The Matrix (1999) are copyrighted, and this repository builds a published site. The film is discussed in the Lesson 2 text and named in the caption of the vat diagram, which carries the same idea without reproducing the film.