But saintliness on the throne, as in the case of St. Louis of France, has its drawbacks in practical work. It is, perhaps, true that the mind of Marcus was more active, and found greater satisfaction, in questioning itself than in anxious inquiry into the state of the Empire. He was not one of those of whom our poet says that they do Duty’s work _and know it not_; and as a consequence his days were not serene and bright. He had a tendency to be morbid, and, like all morbid men, he was serious even to sadness. It has been well said of him that he is always insisting on his faith in a universe in which, nevertheless, he can find nothing but disappointment. His sensitiveness about his duty sometimes warped his judgment and blunted his discernment of character. At the outset he made a bad blunder in dividing the imperial power with his brother by adoption, Lucius Verus, who had little principle and much leaning to pleasure. To him he committed the charge of a war with Parthia which became inevitable, and though the Roman arms were successful, this was not due to the skill or energy of either Marcus or Verus. Had a strong scientific mind been in command, it might have been possible to avert or mitigate a calamity which now fell on the Mediterranean world, and had a share, perhaps a large one, in the decay and fall of the Empire. The legions brought back with them from the East one of the most terrible plagues known to history, which can only be compared for its effects with the Black Death in the fourteenth century. Not only in the East, but nearer home, Marcus had to meet formidable foes who broke through the frontiers with which Hadrian had taken such pains. Pushed forward by pressure from the rear, German tribes unwillingly made their way into Roman territory, overran the new province of Dacia, crossed the Danube, and even passed over the Alps into Italy. Marcus’s difficulties were great, but he met them with patience and courage. The pestilence had so greatly thinned the population that both men and money were wanting for the war, and the struggle to drive back the unwilling invaders was prolonged for thirteen years. It was still going on when Marcus died of fever in camp at Vienna. As he closed his eyes in his tent he must have felt that he had spent himself in vain, and that evil days were in store for the Empire. He left a worthless son, Commodus, who failed to understand the danger, and let things go.