6 JAN 2026

Day 6

Custom is the great guide of human life.

David Hume · An Enquiry Concerning Human Understanding

A bronze wine jug with a bulbous body, high arching handle, and trefoil spout, decorated with engraved spirals and inlaid with red coral. A small bronze duck sits at the base of the spout.

I · THE OBJECT · BRITISH MUSEUM

The Basse-Yutz Flagons

La Tène Celtic · 5th century BC · Copper alloy, coral, enamel

Two bronze wine jugs made north of the Alps, shaped like Etruscan vessels, inlaid with Mediterranean coral, and fitted with a duck that swims toward the pouring wine.

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II · THE IDEA · ARTIFICIAL INTELLIGENCE

Backpropagation

Foundations · Machine learning · 1960s–1980s, independently rediscovered several times

A neural network has millions of weights, each contributing to the final output. Backpropagation computes how much to adjust every single one, in a single backwards pass through the graph.

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Reddish-brown rock paintings on a pale sandstone surface showing cattle with varied markings, human figures with rounded heads, and overlapping images of animals from different periods.

III · THE WORK · ART HISTORY

The Rock Art of Tassili n'Ajjer

Tassili n'Ajjer plateau, south-eastern Algeria · Neolithic and earlier · Pigment on sedimentary rock

Cattle graze, swimmers dive, hunters track game across sandstone walls in the central Sahara. The paintings record a climate that disappeared six thousand years ago.

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