This is a book about laws. Not, however, about the laws of which we learned in science classes at school: “scientific laws”. It is rather about those universalities which govern the world of facts, what Swartz calls “physical laws”—although this language is slightly misleading because the term is intended to cover the living as well as the non-living world. Of course, it may well be that a scientific law (like Boyle's law) does capture the essence of a physical law, but not necessarily or (apparently) usually. A physical law by definition can never be false, whereas (as Michael Scriven pointed out some years ago) almost paradoxically nearly all (if not all) scientific laws are false.