Number rules the universe.— Pythagors One of man's noblest acquisitions in the intellectual sphere is the concept of number. By number, the phenomena of quantity, measurement, and logic are achieved; through operation with these elements the course of man's behavior and his basic philosophy have advanced from the relatively simple and mystical synthesis of Pythagoras to the development of symbolic logic and functions of complex variables. Despite the basic importance of number operations, "the language of science," to the growth of man's world outlook, few detailed studies of the disturbances of this process have appeared in neurological literature since the monumental compilation of Henschen.1 As one perused Henschen's approximately 110 abstracts and the original sources that he utilized in his study of acalculia, it was evident that the term acalculia in his practice included disturbances in number recognition as well as in arithmetical operations. Although acalculia, in this broad