The Black Finger (1923)

Paradise Lost: Book 7, Line 339 by John Martin (1827)

I have just seen a most beautiful thing

      Slim and still

Against a gold, gold sky,

A straight black cypress,

      Sensitive,

      Exquisite,

      A black finger

      Pointing upwards.

Why, beautiful still finger, are you black?

And why are you pointing upwards?