They preserved peace by a constant preparation for war; and while justice regulated their conduct, they announced to the nations on their confines, that they were as little disposed to endure, as to offer an injury. The military strength, which it had been sufficient for Hadrian and the elder Antoninus to display, was exerted against the Parthians and the Germans by the emperor Marcus. The hostilities of the barbarians provoked the resentment of that philosophic monarch, and, in the prosecution of