 Bertrand Russell quickly incorporated NAND into Principia Mathematica. Sheffer’s functions have also been a great economy to the assembly line symbol manipulation of computers (as witnessed by the popularity of NAND gates and NOR gates). However, human beings have trouble achieving fluency with Sheffer’s connectives. Even Sheffer translates them negatively. Psychologically, the phrases ‘either not p or not q’ and ‘neither p nor q’ are each heard as a double dose of negation rather than as an alternative to negation.