of his mother, but the so-called knowing ("Erkennen") is a recognition
(Wiedererkennen) which presupposes a very firm _association of the
memory-images_. This fundamental function attached to the memory can
have but a slow development, because it demands an accumulation of
memory-images and precision in them.

In the second three months it is so far developed, at least, that
strange faces are at once known as strange, and are distinguished from
those of parents and nurse; for they excite astonishment or fear
(crying) while the faces of the latter do not. But the latter, if
absent, are not yet, at this period, missed by most children. Hence it
is worthy of note that a girl in her twelfth month recognized her
nurse after six days' absence, immediately, "with sobs of joy," as the
mother reports (Frau von Struempell); another recognized her father,
after a separation of four days, even in the tenth month (Lindner).

In the seventh month my child did _not_ recognize his nurse, to whom
he had for months been accustomed, after an absence of four weeks.
Another child, however, at four months noticed at evening the absence
of his nurse, who had been gone only a day, and cried lustily upon the
discovery, looking all about the room, and crying again every time
after searching in vain (Wyma, 1881). At ten months the same child
used to be troubled by the absence of his parents, though he bore
himself with indifference toward them when he saw them again. At this
period a single nine-pin out of the whole set could not be taken away
without his noticing it, and at the age of a year and a half this
child knew at once whether one of his ten animals was missing or not.
In the nineteenth and twenty-first months my boy recognized his father
immediately from a distance, after a separation of several days, and
once after two weeks' absence; and in his twenty-third month his joy
at seeing again his playthings after an absence of eleven and a half
weeks (with his parents) was very lively, great as was the child's
forgetfulness in other respects at this period. A favorite toy could
often be taken from him without its being noticed or once asked for.
But when the child--in his eighteenth month--after having been
accustomed to bring to his mother two towels which he would afterward
carry back to their place, on one occasion had only one towel given
back to him, he came with inquiring look and tone to get the second.

This observation, which is