re the _immediate_ results upon consciousness of
nerve currents as they enter the brain, and before they have awakened
any suggestions or associations with past experience. But it is obvious
that _such immediate sensations can be realized only in the earliest
days of life_."

THE ATTRIBUTES OF SENSATION.--Sensations differ from each other in at
least four respects; namely, _quality_, _intensity_, _extensity_, and
_duration_.

It is a difference in _quality_ that makes us say, "This paper is red,
and that, blue; this liquid is sweet, and that, sour." Differences in
quality are therefore fundamental differences in _kind_. Besides the
quality-differences that exist within the same general field, as of
taste or vision, it is evident that there is a still more fundamental
difference existing between the various fields. One can, for example,
compare red with blue or sweet with sour, and tell which quality he
prefers. But let him try to compare red with sweet, or blue with sour,
and the quality-difference is so profound that there seems to be no
basis for comparison.

Differences in _intensity_ of sensation are familiar to every person who
prefers two lumps of sugar rather than one lump in his coffee; the sweet
is of the same quality in either case, but differs in intensity. In
every field of sensation, the intensity may proceed from the smallest
amount to the greatest amount discernible. In general, the intensity of
the sensation depends on the intensity of the stimulus, though the
condition of the sense-organ as regards fatigue or adaptation to the
stimulus has its effect. It is obvious that a stimulus may be too weak
to produce any sensation; as, for example, a few grains of sugar in a
cup of coffee or a few drops of lemon in a quart of water could not be
detected. It is also true that the intensity of the stimulus may be so
great that an increase in intensity produces no effect on the sensation;
as, for example, the addition of sugar to a solution of saccharine would
not noticeably increase its sweetness. The lowest and highest intensity
points of sensation are called the lower and upper _limen_, or
threshold, respectively.

By _extensity_ is meant the space-differences of sensations. The touch
of the point of a toothpick on the skin has a different space quality
from the touch of the flat end of a pencil. Low tones seem to have more
volume than high tones. Some pains feel sharp and others dull and
diffuse. The warmth