"We could not understand why the calculation of Lilienthal and others were so much in error."

"The greatest value of our experiments has been their negative results."

"The aeroplane will be a great factor in bringing together the different nations of the earth."

"The problem was not to build a machine that would fly, but to build a machine that would fly safely."

"It is not in the nature of man to be content with things as they are."