Woodward and Hoffman once jested that a very powerful Maxwell demon could seize a molecule of cyclobutene at its methylene groups and tear it open in a disrotatory fashion to obtain butadiene (Angew. Chem., Int. Ed. 1969, 8, 781-853). Half a century later, Cameron, Brandon & colleagues have studied exactly how hard that demon needs to twist and some of the structural factors that influence it. Their paper on the topic, “Substituent Effects in Mechanochemical Allowed and Forbidden Cyclobutene Ring-Opening Reactions,” has been published at JACS! Congrats to all involved!