Unlike an institutionalized single-party dictatorship, such as Mexico's old system under the Institutional Revolutionary Party, authority in Venezuela can't migrate easily from one leader to the next because the power structures are not mightier than the person who embodies them. Mexican presidents were almighty but only during their six-year term, after which they were vilified by their successor so the power structures could remain under a veneer of renewal. In Venezuela, no such arrangement exists, which is why a month ago, soon after his re-election to a fourth term, Mr. Chavez revealed that his cancer had resurfaced and asked Venezuelans to choose Nicolás Maduro, whom he had hastily appointed vice-president, should he be unable to go on.