306	THE DISCOVERY OF THE CHILD
At this stage, therefore, one is perfecting language itself by
degrees, as the hearing perceives better the sounds composing words,
and the psycho-motor paths are becoming better adapted to
articulation.
It is this early field of spoken language which has its own
beginning and its own course of development leading, by way
of perceptions, to the perfecting of the original mechanism of
language itself. And at this stage there is established what we
call articulate language, which will then be the medium which
man will make use of to express his thoughts, and which man will
have great difficulty in improving or correcting once it has been
fixed. In fact, sometimes higher education is accompanied by
imperfect speech, which hinders the aesthetic expression of
thought.
The development of articulate speech occurs between the ages
of two and five—the age of perceptions, in which the attention of
the child is spontaneously directed to external objects and the
memory is particularly retentive. This is also the age of mobility
when all the psycho-motor tracts have become usable, and the
muscular mechanism is fixed. At this period of life, by the mys-
terious linking up of the auditory tracts and the motor tracts of
articulate language, it seems that the auditory perceptions have
power to excite the complicated movements of articulate speech,
which develops instinctively under these stimuli as if awakening
from the sleep of heredity. It is well known that only at this age
is it possible to acquire all the characteristic modulations of a
language, which it is useless to try and establish later. The
mother tongue is pronounced well because it is fixed in childhood,
and the adult who learns to speak a new language must carry into
it the imperfection which marks the language of the foreigner.
Only children who, below seven years of age, learn several
languages at the same time, are able to perceive and reproduce
the characteristic modulations of accent and pronunciation.
In the same way, the defects acquired in childhood, like dialect
errors, or others due to bad habits, cannot be cured in the adult.