Euler's Eyes
2026-10-11
Image credits
Historical portrait
The portrait of Leibniz painted by Christoph Bernhard Francke around 1695 comes from Wikimedia Commons and is in the public domain. We use the 960-pixel thumbnail provided by Commons, without editing.
Blog figures
The cover and the sketch of the multiplication $23\times14$ are original illustrations. The sketch explains the calculation and does not reproduce the mechanism of the historical machine.
The interactive figures for the eight bits, the terms of the product rule and the sums of the series for π were created for this trail. The examples in the text let you follow the calculations even without JavaScript.
Record
The file data/leibniz_imagens.json records the source, licence, verification date and SHA-256 hash of the portrait. The historical sources for each topic are listed at the end of each post.
Additional historical images
These images come from Wikimedia Commons. The source, licence and SHA-256 hash of each one are recorded in data/leibniz_imagens.json.
- Binary table from Leibniz’s paper (1703): G. W. Leibniz (1703) · Wikimedia Commons · public domain
- Diagram of the I Ching hexagrams sent by Bouvet (1701): Joachim Bouvet and G. W. Leibniz · Wikimedia Commons · public domain
- Leibniz’s calculating machine in Dresden: Kolossos · Wikimedia Commons · CC BY-SA 3.0
- First page of the Nova methodus (1684): G. W. Leibniz · Wikimedia Commons · public domain