„Oczywistość” to najbardziej niebezpieczne słowo w matematyce.”
„Obvious” is the most dangerous word in mathematics.
Źródło: Mathematics, queen and servant of science http://books.google.pl/books?ei=0HjTTKn2Gcf84Abh8vz4Aw&ct=result&id=A_c0AAAAMAAJ&dq=Obvious+%22is+the+most+dangerous+word+in+mathematics&q=%27Obvious%27+is+the+most+dangerous+word+in+mathematics#search_anchor, McGraw-Hill, 1951, s. 16.