 Jevons (1864) gave sharp criticisms on the shortcomings of  Boole’s algebra of logic and abandoned it to create the first version of modern Boolean algebra. (He did not have the unary complement operation that is now standard, but instead used De Morgan’s convention that the complement of a class \(A\) is \(a\).) The title of Jevon’s 1864 book started out with the words Pure Logic, referring to the fact that his version of the algebra of logic had been cleansed from connections to the algebra of numbers. The same point would be made in the introduction to Whitehead and Russell’s Principia Mathematica, that they had adopted the notation of Peano in part to free their work from such connections. 