Viviparous

quadrupeds utter vocal sounds of different kinds, but
they have no power of converse. In fact, this power, or language, is
peculiar to man. For while the capability of talking implies the
capability of uttering vocal sounds, the converse does not hold
good. Men that are born deaf are in all cases also dumb; that is, they
can make vocal sounds, but they cannot speak. Children, just as they
have no control over other parts, so have no control, at first, over
the tongue; but it is so far imperfect, and only frees and detaches
itself by degrees, so that in the interval children for the most
part lisp and stutter.