 Fourth, teasing out the contours of a concept such as causation from a body of discourse such as the law is not (just) a matter of quoting or paraphrasing explicit legal definitions of that concept, no matter how authoritative such definitions purport to be. Legal definitions of causation are only the start of an analysis of what “cause” means in law. Also needed are two other items. One is the implicit concept of cause to be teased out from usages of the concept in propositions of law. Complex legal concepts as used in the decided cases will only rarely coincide completely with official legal definitions (which Roscoe Pound [1910] called, respectively, “the law in action” and “the law in the books”), even when such definitions speak univocally in favor of some particular concept.