A particular interest attaches to the study of the wings of insects, because, in some respects, they act more after the manner of human inventions for aerial locomotion than do the wings of any other flying creature. Though man has never been successful in equipping himself with wings, and has largely given up the hope of acquiring them, he has succeeded in making machines that will fly; and, whether his craft is lighter than air or heavier than air, its driving mechanism is a set of rotating blades, the nearest counterparts of which in the animal world are the rapidly-whirring wings of certain insects.

At quite short notice I was asked to deliver this paper and told at the same time that I must make it popular and not adhere too much to technicalities. This makes it very difficult for me.

On the assumption that for winged flight a man would have to rely on the phasic activity of his muscles (that is to say on an activity induced by nerve impulses from the brain at a rate of 50 per second, or thereabouts) it is easy to believe that for man such flight is impossible.