of a quality. Extension of the quality in a subject is to be 
     represented by a horizontal line, while the qualitative 
     intensities at different points in the subject are to be 
     represented by perpendiculars erected on the extension or 
     subject line. In the case of motion, the line of extension 
     represents time, and the line of intensity, velocity. (p. 33)

     Clagett presents the treatise of Nicholas of Oresme “On 
the Configurations of Qualities” in which Oresme says: “Every 
measurable thing except numbers is conceived in the manner of 
continuous quantity.” This recalls us to the Greek world in 
which as Tobias D. Dantzig points out in his Number: The  
Language of Science  (pp. 141­2):

     The attempt to apply rational arithmetic to a problem in 
     geometry resulted in the first crisis in the history of