circumstances, or admit of the addition of new arms, or the indefinite expansion of an old one. However loose and seemingly flexible, it was rigid in its uniformity; it never altered; it remained under the thirtieth Arsaces such as it had been under the first, improved in details, perhaps, but essentially the same system. The Romans, on the contrary, were ever modifying their system, ever learning new combinations or new manoeuvres or new modes of warfare from their enemies. They met the Parthian tactics of loose array, continuous distant missiles, and almost exclusive employment of cavalry, with an increase in the number of their own horse, a larger employment of auxiliary irregulars, and a greater use of the sling. At the same time they learnt to take full advantage of the Parthian inefficiency against walls, and to practice against them the arts of pretended retreat and ambush. The result was, that Parthia found she could make no impression upon the dominions of Rome, and, having become persuaded of this by the experience of a decade of years, thenceforth laid aside for ever the idea of attempting Western conquests. She took up, in fact, from this time, a new attitude, Hitherto she had been consistently aggressive. She had labored constantly to extend herself at the expense successively of the Bactrians, the Scythians, the Syro-Macedonians, and the Armenians. She had proceeded from one aggression to another, leaving only short intervals between her wars, and had always been looking out for some fresh enemy. Henceforth she became, comparatively speaking, pacific. She was content for the most part, to maintain her limits. She sought no new foe. Her contest with Rome degenerated into a struggle for influence over the kingdom of Armenia; and her hopes were limited to the reduction of that kingdom into a subject position.