Final answer:
The subject of Goya's Caprices #43, The Sleep of Reason Produces Monsters, is the role of reason and imagination in human society.
Step-by-step explanation:
The subject of Francisco Goya's Caprices #43, The Sleep of Reason Produces Monsters, 1799, is the role of reason and imagination in human society. Goya explores the concept that when reason is abandoned, it allows for the emergence of fantastical and monstrous elements. However, when reason is united with imagination, it becomes the source of artistic inspiration and wonder.