o not rest exclusively on observation. Besides, in this
matter, even two children hardly agree. According to my observations, I
am compelled in spite of this disagreement to lay down the proposition
as valid for all healthy children, that the greatly _preponderating
majority of the sounds the child makes use of after learning verbal
language, and many other sounds besides these, are correctly formed by
him within the first eight months_, not intentionally, but just as much
at random as any other utterance of sound not to be used later in
speech, not appearing in any civilized language. I will only mention as
an example the labio-lingual explosive sound, in which the tip of the
tongue comes between the lips and, with an expiration, bursting from its
confinement is drawn back swiftly (with or without tone). All children
seem to like to form this sound, a sound between _p_, _b_, and _t_, _d_;
but it exists in few languages.

Among the innumerable superfluous, unintentional, random, muscular
movements of the infant, the movements of the muscles of the larynx,
mouth, and tongue take a conspicuous place, because they ally
themselves readily with acoustic effects and the child takes delight
in them. It is not surprising, therefore, that precisely those
vibrations of the vocal cords, precisely those shapings of the cavity
of the mouth, and those positions of the lips, often occur which we
observe in the utterance of our vowels, and that among the
child-noises produced unconsciously and in play are found almost all
our consonants and, besides, many that are used in foreign languages.
The plasticity of the apparatus of speech in youth permits the
production of a greater abundance of sounds and sound-combinations
than is employed later, and not a single child has been observed who
has, in accordance with the principle of the least effort (_principe
du moindre effort_) applied by French authors to this province,
advanced in regular sequence from the sounds articulated easily--i. e.,
with less activity of will--to the physiologically difficult;
rather does it hold good for all the children I have observed, and
probably for all children that learn to speak, that many of the sounds
uttered by them at the beginning, in the speechless season of infancy,
without effort and then forgotten, have to be learned afresh at a
later period, have to be painstakingly acquired by means of imitation.

Mobility and perfection in the _technique_ of s