This article provides a comprehensive re-analysis of one of the thorniest problems of criminal jurisprudence, when it is proper to convict a defendant who has attempted the impossible. I begin by demonstrating that, contrary to received academic and judicial opinion, the common law defense of impossibility to a charge of attempt is both well-grounded and perfectly intelligible, being capable of accurate expression in a single sentence. I then account for the confusion regarding the defense by showing how the early courts that applied it were saying one thing while doing another, and how commentators and subsequent judges became misled by focusing on what the courts said rather than what they did. After showing that the defense is intelligible, I then show that it is normatively justified as well. I do this in two steps. First, I demonstrate that there is a principled distinction between moral and criminal responsibility, that the arguments for the rejection of the impossibility defense rest on an improper conflation of the two, and that a correct understanding of the nature of criminal responsibility undermines the force of these arguments. Second, I show that there is an inherent liberal bias built into the Anglo-American criminal law that supplies a principled basis for retaining the defense. I conclude the article by proposing a definition for attempt that both encompasses the defense and grounds it on a firm theoretical basis.