proportion is there between the structural alteration and the
functional result? Is it not perfectly obvious that the alteration is
of the minutest kind, yet that slight as it is, it has produced an
infinite difference in the performance of the functions of these two
instruments?

Well, now, apply that to the present question. What is it that
constitutes and makes man what he is? What is it but his power of
language--that language giving him the means of recording his
experience--making every generation somewhat wiser than its
predecessor,--more in accordance with the established order of the
universe?

What is it but this power of speech, of recording experience, which
enables men to be men--looking before and after and, in some dim sense,
understanding the working of this wondrous universe--and which
distinguishes man from the whole of the brute world? I say that this
functional difference is vast, unfathomable, and truly infinite in its
consequences; and I say at the same time, that it may depend upon
structural differences which shall be absolutely inappreciable to us
with our present means of investigation. What is this very speech that
we are talking about? I am speaking to you at this moment, but if you
were to alter, in the minutest degree, the proportion of the nervous
forces now active in the two nerves which supply the muscles of my
glottis, I should become suddenly dumb. The voice is produced only so
long as the vocal chords are parallel; and these are parallel only so
long as certain muscles contract with exact equality; and that again
depends on the equality of action of those two nerves I spoke of. So
that a change of the minutest kind in the structure of one of these
nerves, or in the structure of the part in which it originates, or of