Therefore in Caligula's time the Roman public became aware that the problem confronting it was a most difficult one. A most exacting public opinion, hesitating between the ideals of two epochs, wished to see united in the empress the best part, both of the ancient and of the modern customs, and was consequently demanding that the second Livia should possess virtually every quality. It was necessary that she should be of noble birth; that is, a descendant of one of those great Roman families which with every year were becoming less numerous, less prolific, less virtuous, and more fiercely divided among themselves by irreconcilable hatreds. This latter was a most serious difficulty; for by marrying into one of these lines, the emperor ran the risk of antagonizing all those other families which were its enemies. The empress, furthermore, must be the model of all the virtues; fruitful, in order to obey the _Lex de maritandis ordinibus_; religious, chaste, and virtuous, that she might not violate the _Lex de adulteriis_; simple and modest, in deference to the _Lex sumptuaria_. She must be able to rule wisely over the vast household of the emperor, full of his slaves and freedmen, and she must aid her husband in the fulfilment of all those social duties--receptions, dinners, entertainments--which, though serious concerns for every Roman nobleman, were even more serious for the emperor. That she should be stupid or ignorant was of course out of the question. In fact, from this time to the downfall of Nero the difficulties of the imperial family and its authority arise not so much from the emperors as from their wives; so that it may truly be said that it was the women who unwittingly dragged down to its ruin the great Julio-Claudian house. [Illustration: A bronze sestertius (slightly enlarged), showing the sisters of Caligula (Agrippina, Drusilla, and Julia Livilla) on one side and Germanicus on the other side.] [Illustration: A bronze sestertius with the head of Agrippina the Elder, daughter of Agrippa and Julia, the daughter of Augustus. She was the wife of Germanicus, and their daughter, Agrippina the younger, was the mother of the Emperor Nero.]