Other inventors had worked from the standpoint
of the telegraph; and they never did, and
never could, get any better results than signs
and symbols. But Bell worked from the standpoint
of the human voice. He cross-fertilized
the two sciences of acoustics and electricity. His
study of "Visible Speech" had trained his mind
so that he could mentally SEE the shape of a word
as he spoke it. He knew what a spoken word
was, and how it acted upon the air, or the ether,
that carried its vibrations from the lips to the ear.
He was a third-generation specialist in the
nature of speech, and he knew that for the transmission
of spoken words there must be "a pulsatory
action of the electric current which is the
exact equivalent of the aerial impulses."

Bell knew just enough about electricity, and
not too much. He did not know the possible
from the impossible. "Had I known more about
electricity, and less about sound," he said, "I
would never have invented the telephone."
What he had done was so amazing, so foolhardy,
that no trained electrician could have thought
of it. It was "the very hardihood of invention,"
and yet it was not in any sense a chance discovery.
It was the natural output of a mind that
had been led to assemble just the right materials
for such a product.