930 PHILOSOPHY OF ZOOLOGY. 
the conditions requisite for receiving this kind of education. 
It is obvious, that there is required a peculiar organization, 
in order, not merely to utter the natural sounds, but to modify 
in tone, intensity, and expression, the sounds which can be 
produced, so as to resemble the notes which are to be acqui- 
red. ‘This capability of the organs to modify themselves to 
acquire particular sounds to any extent, only lasts during the 
period of youth. Afterwards, the muscles of the voice are not 
so obedient to the will, and it becomes difficult to learn to 
pronounce readily, sounds to which we have not been previ- 
ously accustomed. 'T’o this cause may be referred the extreme 
difficulty of ceasing to use the accent of one’s native tongue, 
and of acquiring that of a foreign language. There is, how- 
ever, a second condition, on which this susceptibility of ae- 
quiring language greatly depends, namely, quickness of 
hearing. In order to learn to imitate sounds, it is neces- 
sary that we be able to discriminate their qualities accu- 
rately, to know what we are to imitate, and determine on 
our degree of success. A delicate ear, therefore, is essen- 
tially requisite, and as it chiefly exists in early life, when 
the organ of hearing is in the soundest state, we may dis- 
cover one reason, at least, why the young learn to pro- 
nounce new sounds more readily than the old. But, even 
with the existence of organs capable of articulating an ac- 
quired language, and a delicate ear to discriminate sounds, 
there is required the desire of imitation to induce us to ex- 
ert these organs in producing-a resemblance to the sounds 
we hear. It often happens, particularly among birds, that 
the power of imitation is scarcely exerted in any other 
manner. 
By attending to the conditions requisite to acquire lan- 
guage, we perceive the reason why persons born deaf are 
at the same time dumb. ‘They do utter, indeed, the sounds 
of natural language, expressive of their feelings, -but as 
