The old word for a tort, going back to the Middle Ages, is a trespass, not in the sense we talk about trespass now as an unauthorized entrance upon land, but rather trespass as it's used, for example, in the Our Father, a wrong, something wrong that one person does to another. And so, if you go all the way back eight or nine hundred years, you see initially the legal system developing this idea of a trespass or a wrong, and then building out various areas in which the law recognizes those wrongs. And so, I think it's helpful in the first few weeks of torts to just get a sense of both what the doctrine is, but also how it has evolved historically and in light of different theoretical understandings of what the tort system is trying to do. Torts is a common law subject, which means that it evolves from the common law system that we inherit from England. And that means that it's a system that's been developed through mostly, although not exclusively, the decisions of courts: courts deciding what causes of action to recognize, what the elements of certain causes of action will be, when plaintiffs should prevail, when defendants should prevail under those elements; but driven primarily by courts rendering decisions. Sometimes people say the common law is judge made law. I'm less fond of that formulation because I do think there are deeper principles of practical reasonableness that the common law system is discovering and elucidating and elaborating upon, but it means that it's driven by the decisions of courts. Having said that, there are lots of areas of law, of tort law, that involve statutes, that involve regulations, so it's a mistake to think that it's purely a subject driven by the decisions of courts. But when we say that something's a common law subject, we mean it's primarily an area of law driven by decisions of courts and not by statutes or codes or constitutions or rules. Common law systems are very focused usually on questions of precedent and of the value of precedence and how a prior precedent bears on a case, so a lot of learning how to think like a lawyer in a common law subject like torts involves drawing analogies. So trying to figure out: what kind of case is this and what cases that we've read or considered or that have been decided in this area, what kinds of cases are similar to the kind of case that is in front of a court, or that's in front of a lawyer if you're trying to advise a client. And so, a lot of common law reasoning is about applying precedence and drawing analogies between one set of cases and the case that's in front of you.