1884.] Moral Epidemics and Contagions. 649 
shown how these morbid conditions where the phenomena 
are isolated, restricted, or exaggerated, according to circum- 
stances, corroborate the law of the transmission and trans- 
formation of the expressive movement and of the reflex 
action to which it gives rise, whilst at the same time the 
law gives the reason of the phenomena. 
By generalising these notions, which are very simple, we 
may explain all those apparent contradictions which the 
contagion of nervous phenomena may present, and reply to 
all objections which may here be raised. 
We will confine ourselves here to recall to mind that the 
law of the transmission and transformation of expressive 
movement as expounded above proves to be of an unexpected 
fecundity, for it explains the propagation to a distance, and 
the contagion of all the phenomena, all the affections, 
which have a cerebral movement as their point of departure. 
Further, by showing that a cerebral movement is trans- 
mitted from brain to brain without losing its nature, and 
that to an identical or analogous cerebral movement there 
correspond identical or analogous phenomena, psychological 
and physiological, we have given the strictly scientific solu- 
tion of a great number of problems which have hitherto been 
considered as inexplicable, and which have been banished 
into the most abstract regions of Philosophy, — such as the 
essential character of natural language in man and in other 
animals; the reason of its spontaneous comprehension, at 
all times and in all places ; the special character of con- 
ventional language and its properties ; the reason of the 
spontaneous comprehension of music and of all the fine 
arts ; the nature and the explanation of their influence, 
physical and moral; and their part in hygiene and in 
therapeutics. 
This law is founded upon no hypothesis, but upon a 
rigorous scrutiny of faCts. The author claims the right of 
insisting on this point, since he has been so scrupulous as 
not to touch upon many questions which he is persuaded 
belong under this law, such as most of those which have 
reference to animal magnetism and to somnambulism. 
He has observed this precaution in order that the ob- 
scurity which rests on these subjects may not give a pre- 
text for misinterpreting the fadts which he has brought 
forward. 
We may now proceed to a general summary. In order to 
demonstrate the principle of the contagion of nervous phe- 
nomena, intellectual and moral, it has been necessary to 
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