How Absurd!

I was researching the history of the word absurd and ended up in the world of maths (not for the first time). Absurd derives from the Latin root surdus, which meant 'hard of hearing'. So something absurd is something that is hard to listen to because it doesn't jibe with what is expected.

It was first recorded in the 16th century by the Welsh mathematician and physician Robert Recorde. He called the result of the subtraction 4–8 an absurd number, although primary school children are now taught the concept of negative numbers.

Then I was fascinated to learn that Robert Recorde is more famously remembered as the inventor of the equals sign. In that same book where he called negative numbers absurd (the first English-language book on algebra), he proposed two parallel lines of equal length to complete a sum since 'noe 2 thynges can be moare equalle'. And the same man introduced the plus and minus signs into the UK (they were actually first recorded in Italy in 1494). Robert Recorde achieved high office too, being not only the king's physician but also the controller of the Royal Mint. An amazing man indeed!