Surely not the similarity of appearance. There are ten thousand others in the country just like it. No, but the photographer set up the film in such a way that according to the laws of optics, the film was forced to receive an image of this house. Thanks for bringing that quotation into the fray. Each sentence, as uttered, is a sign instance.
Every cat is a cat.
Every dog is a dog. Every unicorn is a unicorn. Okay, I will try to remember that you talk this way.