rational argument can be conducted with some prospect of success 

only so long as the emotionality of a given situation does not exceed 

a certain critical degree. 

if the affective temperature rises above this level, 

the possibility of reason’s having any effect ceases 

and its place is taken by slogans and chimerical wish fantasies. 

that is to say, a sort of collective possession results 

which rapidly develops into a psychic epidemic.

                                                                                                 -carl jung