1 1 6 Sympathetic action a common property. 



cate that they have been artificially made to appear 

 correct. 



Sympathetic action or propagation of similar influ- 

 ence by immediate impulse, is a property of all the 

 natural forms of energy, as well as of mind. Similar 

 actions are propagated thus in all kinds of dead 

 substances, as well as in the living brain. Matter is 

 sympathetic to sound in the phenomena of singing- 

 flames, and a vibrating string responds to a particular 

 note in obedience to well-known laws. Iodide of 

 nitrogen may be caused to explode by the influence of 

 a particular note from a fiddle. In the phenomena of 

 light, with a spectroscope, a luminous gas is sympa- 

 thetic with, and emits and aborbs, only particular 

 kinds of luminous rays. In chemical action also, 

 combustion excites combustion, ferment excites 

 ferment, infection communicates infection, and the 

 similar chemical change is transmitted from molecule 

 to molecule. Mental excitement and disease in one 

 person, often excite similar phenomena in another, as 

 is seen in " religious revivals," and well-known epi- 

 demics, such as the "'dancing mania," " preaching 

 epidemics," the " leaping ague/' the " mewing con- 

 tagion," etc., etc., (See " Epidemics of the Middle 

 Ages," by Hecker ; Sydenham Society publications ; 

 also Carpenter's Mental Physiology, p. 312.) Like 

 excites like in the actions of each of the forces of 

 nature ; both in physical, chemical, and mental action, 

 the kind of impulse transmitted is similar, unless 

 conditions exist which transmute it. Dynamite, 



