550 WOVUM ORGANUM. [BOOK 1L 



body check, subdue, reduce, and regulate the others, and force 

 them to unite, separate, stand still, move, or assume a certain 

 position, not from any inclination of their own, but according to 

 a certain order, and as best suits the convenience of the 

 governing part, so that there is a sort of dominion and civil 

 government exercised by the ruling part over its subjects. The 

 motion is very conspicuous in the spirits of animals, where, as 

 long as it is in force, it tempers all the motions of the other 

 parts. It is found in a less degree in other bodies, as we have 

 observed in blood and urine, which are not decomposed until 

 the spirit, -which mixed and retained their parts, has been emitted 

 or extinguished. Nor is this motion peculiar to spirits only, 

 although in most bodies the spirit predominates, owing to its 

 rapid motion and penetration ; for the grosser parts predominate 

 in denser bodies, which are not tilled with a quick and active 

 spirit (such as exists in quicksilver or vitriol), so that unless this 

 check or yoke be thrown off by some contrivance, there is no 

 hope of any transformation of such bodies. And let not any 

 one suppose that we have forgotten our subject, because we 

 speak of predominance in this classification ot motions, which is 

 made entirely with the view of assisting the investigation of 

 wrestling instances, or instances of predominance. For we do 

 not now treat of the general predominance of motions or powers, 

 but of that of parts in whole bodies, which constitutes the par 

 ticular species here considered. 



Let the seventeenth motion be the spontaneous motion of 

 revolution, by which bodies having a tendency to move, and 

 placed in a favourable situation, enjoy their peculiar nature, 

 pursuing themselves and nothing else, and seeking, as it were, to 

 embrace themselves. For bodies seem either to move without 

 any limit, or to tend towards a limit, arrived at which they 

 either revolve according to their peculiar nature, or rest. Those 

 which are favourably situated, and have a tendency to motion, 

 move in a circle with an eternal and unlimited motion ; those which 

 are favourably situated and abhor motion, rest. Those which are 

 not favourably situated move in a straight line (as their shortest 

 path), in order to unite with others of a congenial nature. This 

 motion of revolution admits of nine differences : 1. with regard 

 to the centre about which the bodies move ; 2. the poles round 

 which they move ; 3. the circumference or orbit relatively to its 

 distance from the centre ; 4. the velocity, or greater or less 

 speed with which they revolve ; 5. the direction of the motion 

 as from east to west, or the reverse ; 6. the deviation from a 

 perfect circle, by spiral lines at a greater or less distance from 

 the centre ; 7. the deviation from the circle, by spiral lines at a 

 greater or less distance from the poles ; 8. the greater or less 

 distance of these spirals from each other; 9. and lastly. th 



