For much of the nineteenth century, a manufacturer's liability for a defective product was hemmed in by the doctrine of privity. A person injured by a defective good could sue only the party from whom he had directly purchased it; absent a contractual relationship, the manufacturer owed him no duty, however careless its workmanship. The rule had a certain logic. Liability, the courts reasoned, ought to track the chain of contracts, so that each party answered only to those with whom it had dealt. To let an injured stranger reach past the retailer to the manufacturer was to impose a duty the manufacturer had never assumed and could not have priced. The privity rule grew untenable as goods came to be mass-produced and distributed through long chains of intermediaries who neither made nor inspected them. The injured consumer was almost never the manufacturer's immediate purchaser, and to deny recovery on that ground was to immunize precisely the party best positioned to prevent the defect. Courts carved out exceptions - for goods 'imminently dangerous' to human life, such as poisons or explosives - but the category proved unstable, for whether a mislabeled drug was more dangerous than a collapsing wheel depended less on the article than on the accident. The decisive break reconceived the manufacturer's duty as sounding not in contract but in tort. The relevant question, on this view, was not whether the plaintiff had bought from the defendant, but whether the defendant should have foreseen that a defect would endanger someone. If the nature of a thing is such that it is reasonably certain to place life and limb in peril when negligently made, then the manufacturer owes a duty of care to all who may foreseeably be harmed, whatever the state of contractual relations. Foreseeability, not privity, became the boundary of obligation. This reframing did not, as is sometimes supposed, abolish limits on liability; it relocated them. Privity had drawn a bright line, easy to administer but arbitrary in result. Foreseeability substituted a standard, just in principle but far harder to apply, for it invited endless argument about how remote a consequence a reasonable manufacturer must anticipate. The manufacturer of a defective tire foresees the driver's injury readily enough; whether it must also answer to a bystander, or to a rescuer hurt in the ensuing crash, the new principle did not say. Later doctrine would push further still, imposing liability without any proof of negligence at all - strict liability - on the theory that a manufacturer who profits from placing goods in commerce should bear the cost of their defects as a matter of enterprise, not fault. But that development, whatever its merits, should not be read back into the earlier one. The move from privity to foreseeability was a reform within the law of negligence, expanding the class of persons to whom a duty was owed; it did not yet dispense with the requirement of fault, and to conflate the two transformations is to misread the sequence by which modern products liability was built.