It is worthy of note that the elder Agrippina and her son Nero were not recalled from their respective islands after the fall of Sejanus. Seclusion in an island did not of itself involve any serious degree of suffering, and we have mention of occasions on which Tiberius selected for his exiles islands which were healthy or otherwise attractive. The exiles were, in fact, simply removed to places from which they could no longer disturb the public peace. Though it had transpired that Agrippina and Nero were to some extent the victims of Drusus and Sejanus, they had shown themselves inclined to be dangerous, and the situation with regard to the succession was now such as to demand exceptional precautions. In his dealings with Agrippina, Tiberius surprises us by his forbearance rather than by his severity. As we do not know the exact nature of the conspiracy of Sejanus, so we do not know the exact degree of guilt of the younger Drusus. Since he was treated with exceptional rigour we may surmise that he was implicated in a plot to depose the Emperor and enter at once upon the coveted succession. After his death Tiberius wrote a letter to the Senate giving a full account of his misdemeanours, an act which is represented to have been scandalous, but was probably necessary. It must be remembered that Sejanus was disgraced because of his practices against Agrippina and Nero; he was immediately killed by the Senate. After his death a deeper plot, and indeed a series of plots, was revealed. An attempt was made to implicate Caligula in the guilt of these dark transactions, but unsuccessfully. It was on this occasion that Tiberius wrote that despairing cry to the Senate in which Tacitus savagely triumphs--“If I know what I am to write to you, Conscript Fathers, or how I am to write to you, or what indeed I should not write to you at such a time, may the gods and goddesses drag me even into greater depths than those into which I feel that I am sinking day by day.” In spite of the perplexities that assailed him, Tiberius did not relax his hold upon Greater Rome. Encouraged by rumours of the Emperor’s failure, the Parthians began to intrigue to reverse the order established on the Eastern frontier of the Empire, but they quickly learned that Tiberius, though aged and beaten upon, had not forgotten his diplomacy and still knew where to find, and how to choose, an able officer who could effectually quell any attempt to trifle with the dignity of the Roman name. The general appointed to settle affairs in the East was Lucius Vitellius, whose son was one day to enjoy a short and very inglorious career as Roman Emperor.