But if I have gotten as far as knowing that the earth is a sphere and its surface the surface of a sphere, then from a small part of the latter,.g., from the magnitude of one degree, I can cognize its diameter and, by means of this, the complete boundary,.e., surface of the earth, determinately and in accordance with a priori principles;' and although I am ignorant in regard to the objects that this surface might contain, I am not ignorant in regard to the magnitude and limits of thedomain that contains them.