not depend upon absolute, but upon relative,
conditions. We have no reason whatever to fancy that mankind served by
the wonderful technique twenty centuries after Christ is happier than
men were under the primitive conditions of twenty centuries before
Christ. The level has changed and has steadily been raised, but the
feelings are dependent, not upon the height of the level, but upon the
deviations from it. Each level brings its own demands in the human
heart; and if they are fulfilled, there is happiness; and if they are
not fulfilled, there is discontent. But the demands of which we know
nothing do not make us miserable if they remain unfulfilled. It is the
change, and not the possession, which has the emotional value. The up
and down, the forward and backward, are felt in the social world, just
as in the world of space the steady movement is not felt, but only the
retardation or the acceleration.

The psychologist knows the interesting psychophysical law according to
which the differences in the strength of our impressions are perceived
as equal, not when the differences of the stimuli are really equal,
but when the stimuli stand in the same relation. If we hear three
voices, the sound has a certain intensity; if a fourth voice is added,
the strength of the sound is swelling; we notice a difference. But if
there is a chorus of thirty voices and one voice is added, we do not
hear a difference at all. Even if five voices are added we do not
notice it. Ten new singers must be brought in for us to hear the sound
as really stronger. And if we have a mighty chorus of three hundred
singers, not even twenty or fifty or even eighty voices would help us
to feel a difference; we need a hundred additional ones. In other
words, the hundred singers which come to help the three hundred do not
make more impression on us than the ten which are added to the thirty,
or the one added to the three. Exactly this holds true for all our
perceptions, for light and taste and touch. The differences upon which
our pleasures and displeasures hang, obey this same law of
consciousness. If we have three pennies, one added gives us a
pleasure, one taken away gives us a displeasure, which is entirely
different from the pleasure or displeasure if one penny is added or
taken away from thirty or from three hundred pennies. In the
possession of thirty, it needs a loss or gain of ten, in the
possession of three hundred the addition or subtraction of a hu