With a gloomy recognition of the realities of life, Domitian used to say that conspiracy against an emperor was never believed till the emperor was killed.(235) Of the first twelve Caesars seven died a violent death. Every emperor from Tiberius to M. Aurelius was the mark of conspiracy. This was often provoked by the detestable character of the prince. But it sometimes sprang from other causes than moral disgust. The mild rule of Vespasian was generally popular; yet even he had to repel the conspiracy of Aelianus and Marcellus.(236) The blameless Nerva, the emperor after the Senate’s own heart, was twice assailed by risings organised by great nobles of historic name.(237) The conspiracy of Nigrinus against Hadrian received formidable support, and had to be sternly crushed.(238) M. Aurelius had to endure with sad resignation the open rebellion of Avidius Cassius.(239) The better emperors, strong in their character and the general justice of their administration, might afford to treat such opposition with comparative calmness. But it was different in the case of a Nero or a Domitian. The conspiracy of Piso and the conspiracy of Saturninus formed, in each case, a climax and a turning-point. Springing from real and justified impatience, they were ruthlessly crushed and followed up with a cruel and suspicious repression which only increased the danger of the despot. “Scelera sceleribus tuenda” sums up the awful tale, in the words of Tacitus, “of the wrath of God and the madness of men.”