The greatest controversy of the drawings though was the subjects and activities that they illustrated. They seemed to document a process or a ceremony. The hill was shown in profile and people were shown engaged in an activity at the bottom of the hill, climbing the hill, and engaged in activity at the top of the hill. At the bottom of the hill they were shown assembling strangely shaped structures which they are then shown as carrying on their backs to the peak. The remarkable thing is that the structures closely resembled the Rogallo hang gliders of today. Even more remarkable is the fact that the figures are shown as running down the hill and soaring into the air apparently to glide back down to the base of the hill. If the drawings are authentic it means that they flew five hundred years before Otto Lillienthal or the Wright Brothers.Perhaps now you can understand why Professor Vogelhund was such a controversial character. He is claiming that man flew in the fifteenth century using hang gliders made of primitive materials but with very sophisticated design.