Green Magic, by Jack Vance

Jack Vance has had a staggeringly successful career, winning the Hugo, the Nebula, the Jupiter, and the Edgar. He's probably the least-known of all the well-known science fiction masters, if that makes sense. (Probably this has to do with the fact that, aside from a TV movie in the 70s, none of his works have been filmed, thank God.)

An old-school writer who came up through the pulp industry, Vance is still writing, even though he's 91 and blind. For perspective, consider that he received a lifetime achievement World Fantasy Award...twenty-two years ago.

This "science fantasy" short story was first published in the Magazine of Fantasy and Science Fiction in 1963, though it seems so fresh and original I've always thought of it as a product of the Dangerous Visions era of the 70s.

http://www.infinityplus.co.uk/stories/green.htm

I realize this is an online cliche along the lines of "I just spit coffee all over my keyboard," but the deeply moving finale of this story literally gives me chills.