Describe the painting "Europe supported by Africa and America" by William Blake, and propose the message the artist is sending through the work.

In "Europe supported by Africa and America", three female figures stand together facing front, touching, in a supportive manner, the central figure. Left and right figures are colored, one black, the other brown or red-skinned; both are holding the white central figure, apparently symbolic of Europe. The message seems to be that white people of Europe or Caucasians depend on the black native Africans and Native Americans to survive.