many times in the Blob, without explaining where they come from. Their virtue is that, if you keep them simple, they are obvious to all thinking people: they show data in a way that is intuitively understandable. It turns out that they have been around (since ~1890) for a long time . . . or maybe a short time - some fields of logic and mathematics must ask "how ever did they manage before Venn diagrams?". They were invented by a philosopher and logician called John Venn whose 180th birthday (04Aug1834) merited a Goodle on the Google home page a while ago. The beautiful, and appropriately simple, stained glass window [L] was commissioned from Maria McClafferty in 1989 by Gonville and Caius College, Cambridge. The inscription reads "JOHN VENN; FELLOW 1857–1923; PRESIDENT 1903–1923." which is no more than the truth, but a lot less than his contribution to mathematics. The maths here are interesting, he was elected President when he was shoving 70 years of age and died in harness at the age of 88. Some people are clearly functional for years after the current official age for retirement. Venn's big year was 1883, when he turned 49. In that year he was elected to the Royal Society, obtained a doctorate (D.Sc.) from his University . . . and returned his dog-collar to the Church of England. He had taken orders in 1859 and obtained "livings" in Surrey and Hertfordshire which brought him an income, although how he reconciled that with being a fellow of his college in Cambridge requires more research. Where did he live? Was he really grateful for railways to shuttle him back and forth between Sunday sermon and weekday senior common room?
Note 1. For those who had a less expensive education than me and are not in the Inner Circle from which Britain's spies were all recruited, I'll point out that Gonville and Caius is pronounced "keys" in the same contractive way that Worcester is "wuster", Cholmondley is "chumley" and Featherstonehaugh is "fanshaw". I hope that little lesson stops you being exposed as a cad and bounder next time you're at Ascot or Covent Garden.
Note 2. It's only the top part of the window that commemorates John Venn, the multi-coloured square below tribs another alumnus of G&C called R.A. Fisher. I'll get round to writing about him in due course but here I'll mention that Richard "I-hate-my-father-so-of-course-I'm-an-atheist" Dawkins called Fisher the "greatest biologist since Darwin".