ABSTRACT
One of the more notable aspects of intellectual endeavour in the High Middle Ages is the disjunction between theoretical knowledge and practical knowledge. This chapter discusses the undoubted though hidden virtue of the lodestone, concerning which philosophers up to the present time give no information, because it is characteristic of good things to be hidden in darkness until they are brought to light by application to public utility. The lodestone selected must be distinguished by four marks-its color, homogeneity, weight and strength. The north pole of one lodestone attracts the south pole of another and conversely. Certain persons who were but poor investigators of nature held the opinion that the force with which a lodestone draws iron, is found in the mineral veins themselves from which the stone is obtained; whence they claim that the iron turns towards the poles of the earth, only because of the numerous iron mines found there.
