stinct. We shall try to point out the primitive behavior
of the child, that reveals the instinct at its lowest terms, and give
some hint also of its importance in adult behavior.

Classification

Of all the instincts, two groups or classes stand out from the rest:
the responses to organic needs, and the responses to other persons.
The first class includes eating, avoiding injury, and many others; the
second class includes the herd instinct, the mating instinct and the
parental instinct, these three and perhaps no others.

{139}

These two groups out, the rest are rather a miscellaneous collection,
including the "random" or playful activity of young children,
locomotion, vocalization, laughter, curiosity, rivalry and fighting.
They might be named the "non-specific instincts", because the stimulus
for each is not easy to specify, being sometimes another person, so
that this group has great social importance, but sometimes being
impersonal. This third class might also be called the "play
instincts", since they are less essential than the other classes for
maintaining the individual life or for propagating the species; and
are, we may say, less concerned with the struggle for existence than
with the joy of living.

Our classification then has three heads:

(1) Responses to organic needs,
(2) Responses to other persons,
(3) Play responses.

Responses to Organic Needs

Something has already been said [Footnote: See above, pp. 79-81, 112.]
of the manner in which an organic state, such as lack of water, acting
on internal sensory nerves, arouses in the nerve centers an adjustment
towards an end-result, and how, if the end-result cannot immediately
be attained, preparatory reactions occur, the preparatory reactions
being in some cases closely attached, by nature, to the main tendency,
and in other cases only loosely attached so that the tendency leads to
trial and error behavior. The reactions that are nearest to the
end-result are likely to be closely attached to the main tendency,
while those that are farther from the end-result are loosely attached.
Thus, in the case of _thirst_, the drinking movement itself is about
all, in man, that is purely instinctive, {140} and the way of getting
water to the mouth, or the mouth to the water, is a matter for trial
and error, and only becomes fixed as the result of a process of
learning. Still less can we mention any specific water-seeking
reactions, in the human be