'A trick is an action or scheme that is designed to deceive, but a trick of the light is something more benevolent, closer as it is to an optical illusion or an architectural charm. A trick can take the form of a prank or a hoax, but a trick of the light isn’t planned. If you trick someone, you deliberately outwit them. But if you encounter a trick of the light, what you see is not a gimmick but a distinct impression: an effect caused by the way the light falls on a thing and makes that thing, which doesn’t exist, appear to be real.' (Introduction)