"Francisco Ayala likens natural selection to the work of a painter who "creates a picture by mixing and distributing pigments in various ways over the canvas. The canvas and the pigments are not created by the artist but the painting is." But of course, an artist does not make random brush strokes on millions of canvases, selecting the one she likes best while discarding the others, only to repeat the process millions of times until a picture emerges. The artist has a preconceived idea in her mind of the picture she will paint and she makes a series of highly coordinated brush strokes to bring her painting into existence. If natural selection is like a painter, natural selection must be an intelligent process."

The link is a whole essay on the use of analogies in thinking about evolution.