280 PSYCHOLOGY AND PREACHING
the dykes thrown up by pride and convention ; and it cannot flow from the lower to the higher levels except under the highest pressure. But emotion spreads readily and rapidly within the class lines. The members of one class, therefore, may be swept by a common emotion which does not cause even a tremor in the breasts of others who rank below or above them in the social scale. For example, the Negroes in our Southern states may be under the spell of a most in tense mental epidemic convulsed by a common fear or a common elation, or wild with religious fanaticism while the whites look on with only an amused interest; and the whites may be " crazed " by a financial panic or a land boom, while the black man pursues the even tenor of his way, mak ing the forest vocal with his plantation melody or the fields ring with his care-free laughter. The Southern states are, however, far from being typical of the middle stage of social development I am now describing. For typical societies of this kind we must look to lands where the social stratification is yet unmodified by the powerful influences of modern in dustrialism.
There are only two conditions under which the excitement prevailing in one class is likely to overleap the social chasm and infect another. If it becomes overwhelming in its in tensity it may spread across class lines. This condition was approximated in the tremendous war excitement that con vulsed Southern society in the early sixties of the last cen tury. In that case the cause of the excitement was one that affected, indirectly at least, the relations of the two classes to one another though fortunately the Negroes had only a dim apprehension of that fact, and were in sympathy with their white masters ; but notwithstanding this, the agitation was only imperfectly communicated to them. If, on the other hand, the excitement grows directly out of the rela tions of the classes to each other and they both are clearly conscious of this, it will spread across the line ; but in this case it will not on the two sides take the form of a single emotion but of two opposite or antagonistic emotions, and
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