[1] There was in the Roman legal system no public prosecutor and virtually no police. Every Roman citizen was supposed to watch over the laws and see that they were not infringed. On his retirement from office, any governor or magistrate ran the risk of being impeached by some young aspirant to political honors, and not infrequently oratory, an art much cultivated by the Romans, triumphed over righteousness. In the earlier period the ground on which charges were usually brought was malversation; in the time of the empire they were also frequently brought under the above-mentioned law _de majestate_. It has been said that this common act of accusation, the birthright of the Roman citizen, the greatly esteemed palladium of Roman freedom, became the most convenient instrument of despotism. Since he who could bring a criminal to justice received a fourth of his possessions and estates, and since it brought the accuser into prominence, delation was recklessly indulged in by the unscrupulous, both for the sake of gain and as a means of venting personal spite. The vice lay at the very heart of the Roman system, and was not the invention of Tiberius. He could hardly have done away with it without overthrowing the whole Roman procedure. V THE SISTERS OF CALIGULA AND THE MARRIAGE OF MESSALINA After the death of Tiberius (37 A.D.), the problem of the succession presented to the senate was not an easy one. In his will, Tiberius had adopted, and thereby designated to the senate as his successors, Caius Caligula, the son of Germanicus, and Tiberius, the son of his own son Drusus. The latter was only seventeen, and too young for such a responsibility. Caligula was twenty-seven, and therefore still very young, although by straining a point he might be emperor; yet he did not enjoy a good reputation. If we except him, there was no other member of the family old enough to govern except Tiberius Claudius Nero, the brother of Germanicus and the only surviving son of Drusus and Antonia. He was generally considered a fool, was the laughing-stock of freedmen and women, and such a gawk and clown that it had been impossible to put him into the magistracy. Indeed, he was not even a senator when Tiberius died. [Illustration: Caligula.]