nstinct affords a good illustration. When the sex-instinct first
matures, the behaviour of an animal in the presence of a mate is
different from its previous behaviour in similar circumstances, but is
not learnt, since it is just the same if the animal has never previously
been in the presence of a mate.

* Though this can only be decided by comparison with other
members of the species, and thus exposes us to the need of
comparison which we thought an objection to Professor Lloyd
Morgan's definition.

On the other hand, a movement is "learnt," or embodies a "habit," if it
is due to previous experience of similar situations, and is not what it
would be if the animal had had no such experience.

There are various complications which blur the sharpness of this
distinction in practice. To begin with, many instincts mature gradually,
and while they are immature an animal may act in a fumbling manner which
is very difficult to distinguish from learning. James ("Psychology," ii,
407) maintains that children walk by instinct, and that the awkwardness
of their first attempts is only due to the fact that the instinct has
not yet ripened. He hopes that "some scientific widower, left alone with
his offspring at the critical moment, may ere long test this suggestion
on the living subject." However this may be, he quotes evidence to show
that "birds do not LEARN to fly," but fly by instinct when they reach
the appropriate age (ib., p. 406). In the second place, instinct often
gives only a rough outline of the sort of thing to do, in which case
learning is necessary in order to acquire certainty and precision in
action. In the third place, even in the clearest cases of acquired
habit, such as speaking, some instinct is required to set in motion
the process of learning. In the case of speaking, the chief instinct
involved is commonly supposed to be that of imitation, but this may be
questioned. (See Thorndike's "Animal Intelligence," p. 253 ff.)

In spite of these qualifications, the broad distinction between instinct
and habit is undeniable. To take extreme cases, every animal at birth
can take food by instinct, before it has had opportunity to learn; on
the other hand, no one can ride a bicycle by instinct, though, after
learning, the necessary movements become just as automatic as if they
were instinctive.

The process of learning, which consists in the acquisition of habits,
has been much studied in various