 Hermann Weyl (1885–1955), one of most versatile mathematicians of the twentieth century, was preoccupied with the nature of the continuum (Bell 2000). In his Das Kontinuum of 1918 he attempts to provide the continuum with an exact mathematical formulation free of the set-theoretic assumptions he had come to regard as objectionable. As he saw it, there is an unbridgeable gap between intuitively given continua (e.g., those of space, time and motion) on the one hand, and the discrete exact concepts of mathematics (e.g., that of real number) on the other. For Weyl the presence of this split meant that the construction of the mathematical continuum could not simply be “read off” from intuition. Rather, he believed that the mathematical continuum must be treated and, in the end, justified in the same way as a physical theory. However much he may have wished it, in Das Kontinuum Weyl did not aim to provide a mathematical formulation of the continuum as it is presented to intuition, which, as the quotations above show, he regarded as an impossibility (at that time at least). Rather, his goal was first to achieve consistency by putting the arithmetical notion of real number on a firm logical basis, and then to show that the resulting theory is reasonable by employing it as the foundation for a plausible account of continuous process in the objective physical world.