Today, across the dailies
Three daily surfaces I run, each on its own audience — a word and where it came from, a U.S. patent worth looking at, a paradox worth re-reading. Three independent rotations; this page is the editorial home that pulls today's pick from each. The dailies live where their readers find them; this is where they sit together.
rehearse
To rehearse is to go over a thing again before its real performance — to run the lines, walk the blocking, practice the speech. The word is, at the root, agricultural: Old French <em>rehercier</em>, "to harrow again," from <em>herce</em>, a harrow — the spiked frame dragged across a plowed field to break the clods and even the soil. To rehearse is to drag the rake back over ground you have already worked: a second pass over the same earth. The funeral <em>hearse</em> is the harrow's sibling — it began as a harrow-shaped frame of spikes set with candles over a coffin. And the farm implement called a <em>harrow</em> in English is, despite being the same tool, a false friend: a separate Germanic word. The word for practice is a word for re-tilling — working the same field a second time until it lies right.
Classifying Apparatus and Method
The barcode. Filed October 20, 1949; granted October 7, 1952. Woodland conceived the design on a Miami Beach as a graduate student — he traced four lines in the sand, drawing on Morse code's logic of dots and dashes. The original patent shows a bullseye (concentric circles), readable from any angle. The linear UPC code came later (Laurer, IBM, 1973). The first product scanned in a real store was a 10-pack of Wrigley's Juicy Fruit gum, June 26, 1974, Marsh Supermarket, Troy, Ohio. The pack is in the Smithsonian.
Russell’s Paradox
Let R be the set of all sets that don’t contain themselves. Does R contain itself?
If yes, it shouldn’t; if no, it should. Russell found the paradox in 1901 while working on his *Principles of Mathematics*; the next year he wrote to Frege pointing out that it undermined the reduction of arithmetic to logic Frege had attempted in *Grundgesetze*. Frege wrote, in the appendix to volume two of his life’s work, that arithmetic now had no foundation he could see. Russell and Whitehead spent ten years on the *Principia Mathematica* trying to repair the damage with a theory of types. The eventual professional solution was Zermelo–Fraenkel set theory’s axiom schema of separation, which forbids forming a set with arbitrary properties. A clean formal repair, but no one has explained why naive set theory was wrong; only that it was. Mathematics rebuilt itself around the absence.