Gin and tonic was invented to combat malaria in British colonies like Java, which leads us to Geneva, where cleanliness is an obsession. Here, tonic water was sealed with a disposable bottle cap, and razors became disposable, leading us to Huntsman's steel, invaluable for making clock springs. We take a little trip through lighthouses, the education of orphans, psycho-physics, the law of the just noticeable difference, which is the idea behind stellar magnitudes, which leads us to discovering the size of the universe.