Abstract: It seems odd that despite the torrent of writing on emergencies and the law after 9/11, no one has systematically examined the view of emergencies held by our greatest judge. Perhaps the problem is that Justice Holmes has so often been subdivided along doctrinal lines. There is the Holmes of free speech law, represented by the majority opinion in Schenck v. United States and by the dissents in Abrams v. United States and Gitlow v. New York. There is the Holmes of property and takings law, represented by the majority opinion in Pennsylvania Coal Co. v. McMahon. There is the Holmes of due process law, represented by the dissents in Lochner v. New York and Tyson & Bro. v. Banton. And no one much talks about the Holmes opinions first upholding and then invalidating emergency rent control, Block v. Hirsh and Chastleton Corp. v. Sinclair, or about the opinion upholding emergency executive detention in Moyer v. Peabody. In what follows, part of my aim is to suggest that what doctrine has put asunder, a focus on emergencies can reunite. Emergencies are a central theme of Holmes's jurisprudence, one that cuts across doctrinal categories and clarifies theoretical puzzles. My central suggestion is that Holmes's judicial and extrajudicial writings, in their best light, implicitly suggest a coherent account of emergencies, law, and constitutional adjudication. I will call this account the epistemic theory of emergencies, with the caveat that I use "theory" not in any rigorous way but just to indicate that Holmes tended to approach questions of emergency powers with a distinctive set of prejudices. We will see that, quite characteristically, Holmes was suggestive but not systematic about his theoretical premises. Despite the ambiguities, however, it is possible to reconstruct a Holmesian account of emergencies that is both plausible and (I hope) theoretically fresh.