"Learning the secret of flight from a bird was a good deal like learning the secret of magic from a magician—something the magician won't tell, and the bird can't tell."

"We have had considerable difficulty in getting the engine to work properly."

"If we worked on the assumption that what is currently regarded as impossible is really impossible, we should never have made any progress."

"The only bird that could speak told us what it knew, but we didn’t understand its language."

"Success in inventing depends on the close observation of nature."