All flight is based upon producing air pressure, all flight energy consists in overcoming air pressure.

Particular honour belongs to those who believed in the possibility of mechanical flight when all the world was against them; not the visionaries because they hoped for it merely, but those who by sheer force of intellect perceived the means by which it could be accomplished and directed their experiments along the right path. ... The name of Lilienthal is now among the most honoured, but curiously his own countrymen were the last to recognize the value of his work.

All flight is based upon producing air pressure, all flight energy consists in overcoming air pressure.

Small sacrifices must be made.

One can get a proper insight into the practice of flying only by actual flying experiments. . . . The manner in which we have to meet the irregularities of the wind, when soaring in the air, can only be learnt by being in the air itself. . . . The only way which leads us to a quick development in human flight is a systematic and energetic practice in actual flying experiments.

Of all the men who attacked the flying problem in the 19th century, Otto Lilienthal was easily the most important. ... It is true that attempts at gliding had been made hundreds of years before him, and that in the nineteenth century, Cayley, Spencer, Wenham, Mouillard, and many others were reported to have made feeble attempts to glide, but their failures were so complete that nothing of value resulted.

But we must admit the possibility that continued investigation and experience will bring us ever nearer to that solemn moment, when the first man will rise from earth by means of wings, if only for a few seconds, and mark that historical moment which heralds the inauguration of a new era in our civilization.