Every character in the novel, it can be said, with the exception of Tempy and Mr. Siles, is a living challenge to our civilization, a challenge that is all the more effective because it springs naturally out of its materials and is not superimposed upon them."
The author emphasizes that every character in the story except for Tempy and Mr. Siles embodies a challenge to their society's existence, making them more formidable because they are organically integrated into the narrative rather than imposed externally.