"I have no ambition to surprise my reader. Castles with unknown passages are not compatible with my homely muse"

In this quote, Anthony Trollope is revealing his writing design and method. He specifies that he has no desire to shock or surprise his readers. Instead, he chooses to stick to a more basic and familiar design, as represented by his "homely muse." Trollope is essentially saying that he does not wish to create elaborate and mystical stories with hidden passages and secrets, but rather he wishes to compose in a manner in which is relatable and comfy for his readers. He values a more uncomplicated and down-to-earth technique to storytelling, rather than relying on sensationalism or intrigue.