e-history.txt Subject: RE: what is "e" As with much of modern mathematics, the symbol "e" was inroduced by Leonhard Euler as "that number whose hyperbolic logarithm = 1" begining in a manuscript written probably in 1727 upon his arrival in Russia. He used it numerous times subsequently, and it appeared in print for the first time in Euler's _Mechanica_ in 1736. Euler is also largely responsible for the current use of the symbol for pi, and he introduced the symbol "i" for SQR(-1). All of these, plus 0 and 1 can be combined in the equality: e^(pi*i) + 1 = 0 See _A history of mathematics (2nd edition)_ by Carl B. Boyer, page 442. John R. Vokey Department of Psychology University of Lethbridge Lethbridge, Alberta CANADA T1K 3M4 vokey@hg.uleth.ca p.s.: although not known for sure, it has been suggested that "e" was chosen for "exponent". Given that he wrote mostly in Latin (and also French), his native language was German, and he was trained in oriental languages, spoke and wrote fluent Russian, and had little difficulty with _any_ European language as he moved from country to country, who knows why he chose the letter "e".