Cardozo's new "rule" exists in no prior case, but is inferrable as a synthesis of the "thing of danger" principle stated in them, merely extending it to "foreseeable danger" even if "the purposes for which it was designed" were not themselves "a source of great danger". "MacPherson" takes some care to present itself as foreseeable progression, not a wild departure. Cardozo continues to adhere to the original principle of "Winterbottom", that "absurd and outrageous consequences" must be avoided, and he does so by drawing a new line in the last sentence quoted above: "There must be knowledge of a danger, not merely possible, but probable." But while adhering to the underlying principle that "some" boundary is necessary, "MacPherson" overruled the prior common law by rendering the formerly dominant factor in the boundary, that is, the privity formality arising out of a contractual relationship between persons, totally irrelevant. Rather, the most important factor in the boundary would be the nature of the thing sold and the foreseeable uses that downstream purchasers would make of the thing.