The labors of these monarchs were overpaid by the immense reward that inseparably waited on their success, by the honest pride of virtue, and by the exquisite delight of beholding the general happiness of which they were the authors. A just but melancholy reflection imbittered, however, the noblest of human enjoyments. They must often have recollected the instability of a happiness which depended on the character of a single man. The fatal moment was perhaps approaching when some licentious youth or some jealous tyrant would abuse, to the destruction, that absolute power which they had exerted for the benefit of their people. The ideal restraints of the senate and the laws might serve to display the virtues, but could never correct the vices, of the emperor. The military force was a blind and irresistible instrument of oppression, and the corruption of Roman manners would always supply flatterers eager to applaud, and ministers prepared to serve, the fear or the avarice, the lust or the cruelty, of their masters. These gloomy apprehensions had been already justified by the experience of the Romans. The annals of the emperors exhibit a strong and various picture of human nature, which we should vainly seek among the mixed and doubtful characters of modern history. In the conduct of those monarchs we may trace the utmost lines of vice and virtue; the most exalted perfection, and the meanest degeneracy of our own species. The mildness of Marcus Aurelius, which the rigid discipline of the Stoics was unable to eradicate, formed, at the same time, the most amiable, and the only defective, part of his character. His excellent understanding was often deceived by the unsuspecting goodness of his heart. Artful men, who study the passions of princes, and conceal their own, approached his person in the disguise of philosophic sanctity, and acquired riches and honors by affecting to despise them. His excessive indulgence to his brother,[46] his wife, and his son exceeded the bounds of private virtue, and became a public injury, by the example and consequences of their vices.