  Weyl’s espousal of the intuitionistic standpoint in the foundations  of mathematics in 1920–21 inevitably led to friction with his  old mentor Hilbert. Hilbert’s conviction had long been that there  were in principle no limitations on the possibility of a full  scientific understanding of the natural world, and, analogously, in  the case of mathematics, that once a problem was posed with the  required precision, it was, at least in principle, soluble. In 1904  he was moved to respond to Emil du Bois-Reymond’s famous declaration  concerning the limits of science, ignoramus et ignorabimus (“we are ignorant and we shall remain ignorant”):