Today's post from @paysmaths @Theoremoftheday was on #EulersIdentity or #EulersEquation \(e^{i\pi} + 1 = 0\) (also given in various equivalent forms), which prompts me to talk about a little historical mystery.

Euler's identity is often held up as as exemplar of mathematical beauty, or called the most beautiful or most elegant equation in mathematics.

But when I was researching my book ‘Form & Number: A History of Mathematical Beauty’ [https://archive.org/details/cain_formandnumber_ebook_large], I was unable to find *any* aesthetic judgement of the equation before the 1940 book ‘Mathematics and the Imagination’ by Kasner & Newman [https://archive.org/details/mathematicsimagi0000edwa_l2s0], where it is called ‘elegant’ (p.103). The earliest explicit judgements of it as *beautiful* that I found are in essays by Le Lionnais in the late 1940s.

Does anyone know of any aesthetic judgements of Euler's equations before 1940? (I know of earlier non-aesthetic judgements like ‘mysterious’ or ‘paradoxical’.)

(The history of aesthetic judgements of Euler's equation is on pp.835–9 of ‘Form & Number’, #OpenAccess at the link above.)

#MathematicalBeauty #MathHist #aesthetics #MathArt #Mathematics