The camera can free still beat of a bird, but Leonardo had to arrest the motion of the wings in his mind, and he drew, hundreds of times, the positions of birds in flight.' A bird makes the same use of its wings and tail in the year as a swimmer does of his arms and legs in the water'. Using the analogy of currents of water and air, he says, 'it's a bird show lowers its wings in make itself more stable upon the air, and support itself with less difficulty, but it is more certain not to be overturned in keeping its wings high than in keeping them low'.