The helms formed on the shoulders of the wings of birds are provided by resourceful nature as a convenient means of deflecting the direct impetus, which often takes place during their headlong flight. For a bird finds it much more convenient to bend by direct force one of the smallest parts of the wings than the whole of them; and the reason why their feathers are made very small and very strong is that they may serve as cover for one another and in doing so arm and fortify each other with marvellous power.
