Meanwhile, at the beginning of this year, Drusus, one of the children of Germanicus, assumed the dress of manhood, with a repetition of the honours decreed by the Senate to his brother Nero. The emperor added a speech, with warm praise of his son for sharing a father's affection to his brother's children. Drusus indeed, difficult as it is for power and mutual harmony to exist side by side, had the character of being kindly disposed or at least not unfriendly towards the lads. And now the old plan, so often insincerely broached, of a progress through the provinces, was again discussed. The emperor's pretext was the number of veterans on the eve of discharge and the necessity of fresh levies for the army. Volunteers were not forthcoming, and even if they were sufficiently numerous, they had not the same bravery and discipline, as it is chiefly the needy and the homeless who adopt by their own choice a soldier's life. Tiberius also rapidly enumerated the legions and the provinces which they had to garrison. I too ought, I think, to go through these details, and thus show what forces Rome then had under arms, what kings were our allies, and how much narrower then were the limits of our empire.
Complete Works of Tacitus. Tacitus. Alfred John Church. William Jackson Brodribb. Sara Bryant. edited for Perseus. New York. : Random House, Inc. Random House, Inc. reprinted 1942.
