It was the duty of Cnaeus Piso to counsel, to restrain, and to aid the young Germanicus, and doubtless also to keep Tiberius informed of all that Germanicus was doing in the East.  When we remember that Tiberius was responsible for the empire, no one will deny him the right of setting a guard upon the young man of thirty-three, into whose hands had been intrusted many and serious interests.  But though this idea was warrantable in itself, it became the source of great woe.  Germanicus was offended, and, driven on by his friends, he broke with Piso.  The latter had brought with him his wife Plancina, who was a close friend of Livia, just as Germanicus had brought Agrippina.  The two wives fell to quarreling no less furiously than their husbands, and two parties were formed in the Orient, one for Piso and one for Germanicus, who accused each other of illegality, extortion, and assuming unwarranted powers; and each thought only of undoing what the other had accomplished.  It is difficult to tell which of the two was right or in how far either was right or wrong, for the documents are too few and the account of Tacitus, clouded by an undiscerning antipathy, sheds no light upon this dark secret.  In any case, we are sure that Germanicus did not always respect the laws and that he occasionally acted with a supreme heedlessness which now and then forced Tiberius to intervene personally, as he did on the occasion when Germanicus left his province with Agrippina in order that, dressed like a Greek philosopher, he might make a tour of Egypt and see that country, which then, as now, attracted the attention of persons of culture.  But at that time, unlike the present, there was an ordinance of Augustus which forbade Roman senators to set foot in Egypt without special permission.  As he had paid no attention to this prohibition, we need not be astonished if we find that Germanicus did not respect as scrupulously as Tiberius wished all the laws which defined his powers and set limits to his authority.

However that may be, the dissension between Germanicus and Piso filled the entire Orient with confusion and disorder, and it was early echoed at Rome, where the party hostile to Tiberius continued to accuse him, out of motives of hatred and jealousy, of forever laying new obstacles in the way of his adopted son.  Livia, too, now no longer protected by Augustus, became a target for the accusations of a malevolent public opinion.  It was said that she persecuted Germanicus out of hatred for Agrippina.  Tiberius was much embarrassed, being hampered by public opinion favorable to Germanicus and at the same time desiring that his sons should set an example of obedience to the laws.