" A beach house,” he said, “doesn’t even have to be on the beach. Though the best ones are. We all like to congregate,” he went on, “at boundary conditions.” “Really?” said Arthur. “Where land meets water. Where earth meets air. Where body meets mind. Where space meets time. We like to be on one side, and look at the other. "

― Douglas Adams , The Ultimate Hitchhiker's Guide to the Galaxy (Hitchhiker's Guide to the Galaxy, #1-5)