Bird flight had always been a recurrent theme of his work, but these gliding paintings represent the apogee of a dream.

At the end of his life he started to research bird flight, in order to pursue one of the great dreams of humanity: to fly.

This article discusses the mechanics of bird flight, with emphasis on the varied forms of bird's wings.

He went to sea again for several years, learning more about wind, weather and bird flight.

This plays a major role in bird flight.