1884 .] Moral Epidemics and Contagions. 575 
The men marching are naturally aided by this movement, 
and follow its impulse spontaneously. 
Persons at rest feel all their limbs more or less agitated 
by the same cadence, and express it instinctively in one or 
another manner. 
This reflex movement determined by sound-waves may 
thus be recognised in a very striking manner. 
But here we are led to another important observation : 
this cadence aids, by the reflex movement, the men who 
have to march, sparing them the fatigue of a movement 
which they would otherwise have to give themselves in a 
direCt manner. 
This explains the reason, hitherto unknown, of analogous 
influences which are observed in a multitude of cases. 
For persons who wish to remain in a state of total rest — 
or, indeed, to aCt in some heterologous manner — these 
sound-waves, when they excite their corresponding reflex 
action, will prove annoying instead of agreeable. Such 
persons will feel fatigued instead of aided, for, in order to 
keep still, they will have to struggle against this reflex 
movement just as we struggle against the reflex movement 
which tends to reproduce yawning, when we do not wish to 
yield to it. 
These considerations are fruitful in consequences. By 
their means we are led to recognise the physical and moral 
influences of music and of all the fine arts,— not forgetting 
eloquence, — to formulate the laws of this influence, and to 
determine with precision their sanitary and therapeutical 
applications. 
This modus agendi of the contagious reflex movement 
explains faCts to which it would seem at first quite inap- 
plicable. 
We may generalise these notions and explain scienti- 
fically a number of faCts which otherwise appear contra- 
dictory. 
Sometimes, for instance, we love gay impressions, whilst 
sometimes we love melancholy impressions. If we have 
motives for giving ourselves up to sadness we have a satis- 
faction in this condition. At such times smiling counte- 
nances, joyous songs, — in a word whatever is gay annoys 
us, because we are obliged to struggle against the reflex 
contagious movement in order to remain in the state which 
we have chosen. On the other hand, everything conducive 
to sadness will please us, because it agrees with our 
condition. Gay impressions fatigue us, and do not readily 
