226 MICHAEL A. HOSKIN 



of the efficient cause of gravity. " Since nothing acts at a 

 distance," he says, " that is, nothing can exert any force in 

 acting where it is not, it is evident, that bodies (if we would 

 speak properly) cannot at all move one another, but by contact 

 and impulse. . . . Yet because besides innumerable other phe- 

 nomena of nature, that universal gravitation of matter . . . 

 can by no means arise from the mutual imj^ulse of bodies 

 (because all impulse must be in proportion to the superficies, 

 but gravity is always in proportion to the quantity of solid 

 matter, and therefore must of necessity be ascribed to some 

 cause that penetrates to the inward substance itself of solid 

 matter) , therefore all such attraction is by all means to be 

 allowed as it is not the action of matter at a distance, but the 

 action of some immaterial cause which perpetually moves and 

 governs matter by certain laws." He goes on to quote several 

 passages from the Opticks, adding the gloss " not bodily 

 impulse " to Newton's " What I call attraction may be per- 

 formed by impulse." *^ 



With the publication of the 1710 edition Clarke's notes 

 assumed almost their final shape. On the title pages Newton's 

 name is actually given greater prominence than those of author 

 and editor; the notes have grown to between one-quarter and 

 one-third the length of the text ^* with a corresponding increase 

 in quality, and they are now displayed as footnotes with 

 references in the index.*^ Clarke left these notes unaltered in 

 the 1718 edition, which suggests that after his famous contro- 

 versy with Leibniz,*'' in which he acted as Newton's champion, 

 he saw little reason to alter his opinions — above all, on the 

 nature of gravity. But he did make a few minor alterations 



"Pp. 50-51. 



** As the title-page of a reissue accurately observes, they have been increased by 

 half. 



*^ The continental edition of 1708 has footnotes, but these are not referenced in 

 the index. The references in the 1710 edition are presumably to the notes Clarke 

 himself regarded as important. 



*" See H. G. Alexander (ed.) , The Leibniz-Clarke Corres^pondence (Manchester: 

 Univ. Press, 1956) . 



