But the alteration in the position of the new kingdom with reference to the Roman is significant. The Arsacids never felt themselves quite on a level with the Caesars. Often as the two states encountered each other in war and peace as powers equal in weight, and decidedly as the view of two great-powers dominated the Roman East (p. 1), there remained with the Roman power a precedence similar to that which the holy Roman empire of the German nation possessed throughout centuries, very much to its hurt. Acts of subjection, such as the Parthian kings took upon themselves in presence of Tiberius (p. 44) and of Nero (52), without being compelled to them by extreme necessity, cannot be at all conceived of on the Roman side. It cannot be accident that a gold coin was never struck under the government of the Arsacids, and the very first Sassanid ruler practised coining in gold; this is the most palpable sign of sovereignty unrestricted by any duties of a vassal. To the claim of the empire of the Caesars alone to the power of coining money for universal circulation the Arsacids without exception yielded, at least in so far that they themselves refrained generally from coining, and left coinage in silver and copper to the towns or the satraps; the Sassanids again struck gold pieces, as did king Darius. The great-kingdom of the East at length demanded its full right; the world no longer belonged to the Romans alone. The submissiveness of the Orientals and the supremacy of the Occidentals were of the past. Accordingly, in place of the relations between Romans and Parthians, as hitherto, always reverting afresh to peace, there now came for generations embittered hostility. [Sidenote: Parthian war of Severus Antoninus.]