GENERATION. S*CT. XXXIX. 8. 



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only; whofe firft link proceeded frorn the great Crea- 

 tor, and which ha\e exifted from the beginning of the 

 cieated univerfe, and are perpetually proceeding. 



2. Thefe caufes may be conveniently divided into- 

 two kinds, efficient and inert caufes, according with 

 the two kinds of entity fuppofed to exifl in the na- 

 tural world, which may be termed matter and fpirit, 

 as propofed in Sect. I. and further treated of in 

 Sect. XIV. The efficient caufes of motion, or new 

 configuration, confift either of the principle of gra- 

 vnatioa, which a6tuares the fun and planets ; or of 

 the principle of particular gravitation, as in elec- 

 tricity, magnetifm, heat ; or of the principle of che- 

 mical affinity, as in combuftion, fermentation, com- 

 bination ; or of the principle of organic life, as in 

 the contraction of vegetable and animal fibres. The 

 inert caufes of motion, or new configuration, con- 

 fift of the parts of matter^ which are introduced 

 tvithin the fpheres of activity of the principles above 

 tlcfcribed. Thus, when an apple falls on the ground, 

 the principle of gravitation is the efficient caufe, 

 and the matter of the apple the inert caufe. If a 

 bar of iron be approximated to a magnet, it may be 

 termed the inert caufe of the motion, which brings 

 thcfe two bodies into contact; while the magnetic 

 principle may be termed the efficient caufe. In the 

 lame manner the fibres, which conftitute the retina, 

 may be called the inert caufe of the motions of that 

 0rg*n in vifion, while the fenforial power may be 

 termed the efficient caufe. 



3. Another moie common diftiibution of the per-* 

 peural chain of caufes and effedts, which conftitute 

 the motions, or changing configurations, of the na- 

 tural world, is into active and paflive. Thus, if a 

 ball in motion impinges againft another ball at reft, 

 and communicates its motion to it, the former ball 

 is faid to act, and the latter to be a6led upon. In 

 this fenfe of the words a ningnet is faid to attract 



iron ; 



