CATENATION OF MOTIONS. SECT. XVIII. 5 



by their effe&s, do to the fenforial power of irritati- 

 on ; as the former is produced by volition without 

 our attention to it, and the latter by irritation with- 

 out our attention to them. 



If on the other hand a train of imagination or of 

 voluntary ideas are excited with great energy, and 

 paffing on with great vivacity, and become difiever- 

 ed by fome violent ftimulus,. as the difcharge of a 

 piftol near one's ear* another circumftance takes 

 place, which is termed SURPRISE; which by ex- 

 citing violent irritation, and violent fenfation, em- 

 ploys for a time the whole fenforial energy, and thus 

 diflevers the pafling trains of ideas, before the pow- 

 er of volition has time to compare them with the 

 jifual phenomena of nature. In this cafe fear is 

 generally the companion of furprife, and adds to 

 our embarraflment, as every one experiences in 

 fome degree when he hears a noife in the dark, 

 which he cannot inftantly account for. This cate- 

 nation of fear with furprife is owing to our perpetual 

 experience of injuries from external bodies in moti- 

 on, unlefs we are upon our guard againft them. See 

 Sett. XVIII. 17. and XIX. %. 



Many other examples of the catenations of animal 

 motions are explained in Se&. XXXVI. on the Peri- 

 04s of Difeafes. 



SECT. 



