When the righteous are in authority, the people rejoice: but when the wicked beareth rule, the people mourn. - Proverbs 29:2
For neither do we say that certain Christian emperors were therefore happy because they ruled a long time, or, dying a peaceful death, left their sons to succeed them in the empire, or subdued the enemies of the republic, or were able both to guard against and to suppress the attempt of hostile citizens rising against them. These and other gifts or comforts of this sorrowful life even certain worshippers of demons have merited to receive, who do not belong to the kingdom of God to which these belong; and this is to be traced to the mercy of God, who would not have those who believe in Him desire such things as the highest good. But we say that they are happy if they rule justly; if they are not lifted up amid the praises of those who pay them sublime honors, and the obsequiousness of those who salute them with an excessive humility, but remember that they are men; if they make their power the handmaid of His majesty by using it for the greatest possible extension of His worship; if they fear, love, worship God; if more than their own they love that kingdom in which they are not afraid to have partners; if they are slow to punish, ready to pardon; if they apply that punishment as necessary to government and defence of the republic, and not in order to gratify their own enmity; if they grant pardon, not that iniquity may go unpunished, but with the hope that the transgressor may amend his ways; if they compensate with the lenity of mercy and the liberality of benevolence for whatever severity they may be compelled to decree; if their luxury is as much restrained as it might have been unrestrained; if they prefer to govern depraved desires rather than any nation whatever; and if they do all these things, not through ardent desire of empty glory, but through love of eternal felicity, not neglecting to offer to the true God, who is their God, for their sins, the sacrifices of humility, contrition, and prayer. Such Christian emperors, we say, are happy in the present time by hope, and are destined to be so in the enjoyment of the reality itself, when that which we wait for shall have arrived. - Augustine, City of God, Book V, Chapter 24 - a king has to be master of himself before he can master people
[He] should be chaste and avoid avarice (iv, 5); he should be learned in letters (iv, 6); he should be humble (iv, 7); he should banish from his realm actors and mimes, buffoons and harlots (iv, 4); he should seek the welfare of others and not his own (iv, 8); he should wholly forget the affections of flesh and blood and do only that which is demanded by the welfare and safety of his subjects; he should be both father and husband to them (iv, 3); he should correct their errors with the proper remedies (iv, 8); he should be affable of speech and generous in conferring benefits; he should temper justice with mercy (iv, 8); . . . he must avoid levity (vi, 23); he is charged with the disposal of the means of the public welfare (vi, 24); and is the dispenser of honour (vi, 26); he must not close his ear to the cries of the poor (vi, 27); he must raise aloft the roof-tree of the Church and extend abroad the worship of religion (vi, 2); he must protect the Church against sacrilege and rapine (vi, 13); and finally, he must ever strive so to rule that in the whole community over which he presides none shall be sorrowful (vi, 6) - Lester Born (“The Perfect Prince,” Speculum 1928) (472-3).
Humility is one of the most essential qualities in a prince (i, 2, 9), and he should be virtuous (i, 1, 10), for his wicked acts are copied by everyone” (summarized by Born, 479). William Perrault makes the same points in his Eruditione Principum: “The prince should often stop to think what he is, who he is, and what sort of creature he is (iii, 6).1 He should be of good character (vi, 7), mild (vi, 1), truthful (i, 7; i, 13; vi, 1), just in his relations with his subjects, and content with his income (vi, 1). He should always act so as to be a pattern for his subjects (vi, 7). Above all he should not be so concerned with the welfare of others that he neglects the care of himself (iii, 1) – the greatest triumph is self conquest (v, 37) -for evil in the prince is widely diffused by his wicked example (vi, 7) - Gilbert of Tournai (Eruditio Regnum et Principum, summarized in Born, 485)
The studies and character of priests and bishops are a potent factor in this matter, I admit, but not nearly so much so as are those of princes. Men are more ready to decry the clergy if they sin than they are to emulate them in their good points. So it is that monks who are really pious do not excite people to follow their example because they seem only to be practicing what they preach. But on the other hand, if they are sinful everyone is shocked beyond measure. But there is no one who is not stimulated to follow in the footsteps of his prince! For this very reason the prince should take special care not to sin, because he makes so many followers in his wrongdoings, but rather to devote himself to being virtuous so that so many more good men may result. - Erasmus, Education of a Christian Prince