George Frederic Watts: Orlando Pursuing the Fata Morgana, 1848.

The subject is taken from Boiardo’s Orlando Inamorato, Book II, cantos viii-ix. The fair Margana, symbolising Fortune or Opportunity, holds captive Rinaldo and other paladins of Charlemagne.—There are larger reproduction of this painting on the web, but this one, from the BBC website, probably has the best overall quality.