VISUAL AND AUDITORY DISHNCTIONS 183
sense which can receive impressions only from movement which
takes place round the hearer.
An education in hearing, if it starts from immobility to pro-
ceed to the perception of noises and sounds caused by movement,
begins from silence.
We have already explained the importance (many-sided) which
our method attaches to silence, which becomes the controlling
factor in the voluntary inhibition of the movements from which
it is derived.
Silence leads also to training in collective effort, for, in order
to obtain silence in a certain place it is essential that all objects
(or people) within it should be completely motionless.
There is no doubt that trying to establish complete silence
ought to awaken keen interest, as indeed happens among the
children, who obtain satisfaction from this research in itself.
(Analyses of independent factors.)
The sense of hearing also gives us a clear idea of what the
first fundamental education of the senses consists in. It consists,
in fact, in being able to hear more.
We hear more (acquire greater acuteness of hearing) when we
can hear slighter noises than before. Education of the senses
leads then to an appreciation of the smallest stimuli, and the
smaller that which is perceived the greater is the seasonal
The education of the senses strengthens in an essential manner
the TrnTnynal appreciation of external stimuli.
For example, a half-deaf person (as Itard has shown so con-
clusively) can be educated to perceive slighter noises than those
which, if he had been left to himself without any education,
generally he could hear before, until by stages, he is led to hear
the ordinary noises which the normal matt hears without any
education in hearing.
And basing his proceedings on this idea, Itard, using a suc-
cession of stimuli which were graded from the strongest to the
lightest, trained many deaf-jmites till they could hear the speaking