How the kindly-disposed and the envious are to be admonished.
(Admonition 11.) Differently to be admonished are the kindly-disposed and the envious. For the kindly-disposed are to be admonished so to rejoice in what is good in others as to desire to have the like as their own; so to praise with affection the deeds of their neighbours as also to multiply them by imitation, lest in this stadium of the present life they assist at the contest of others as eager backers, but inert spectators, and remain without a prize after the contest, in that they toiled not in the contest, and should then regard with sorrow the palms of those in the midst of whose toils they stood idle. For indeed we sin greatly if we love not the good deeds of others: but we win no reward if we imitate not so far as we can the things which we love. Wherefore the kindly-disposed should be told that if they make no haste to imitate the good which they applaud, the holiness of virtue pleases them in like manner as the vanity of scenic exhibitions of skill pleases foolish spectators: for these extol with applauses the performances of charioteers and players, and yet do not long to be such as they see those whom they praise to be. They admire them for having done pleasing things, and yet they shun pleasing in like manner. The kindly-disposed are to be told that when they behold the deeds of their neighbours they should return to their own heart, and presume not on actions which are not their own, nor praise what is good while they refuse to do it. More heavily, indeed, must those be smitten by final vengeance who have been pleased by that which they would not imitate.
The envious are to be admonished how great is their blindness who fail by other men's advancement, and pine away at other men's rejoicing; how great is their unhappiness who are made worse by the bettering of their neighbour, and in beholding the increase of another's prosperity are uneasily vexed within themselves, and die of the plague of their own heart. What can be more unhappy than these, who, when touched by the sight of happiness, are made more wicked by the pain of seeing it? But, moreover, the good things of others which they cannot have they might, if they loved them, make their own. For indeed all are constituted together in faith as are many members in one body; which are indeed diverse as to their office, but in mutually agreeing with each other are made one. Whence it comes to pass that the foot sees by the eye, and the eyes walk by the feet; that the hearing of the ears serves the mouth, and the tongue of the mouth concurs with the ears for their benefit; that the belly supports the hands, and the hands work for the belly. In the very arrangement of the body, therefore, we learn what we should observe in our conduct. It is, then, too shameful not to act up to what we are. Those things, in fact, are ours which we love in others, even though we cannot follow them; and what things are loved in us become theirs that love them. Hence, then, let the envious consider of how great power is charity, which makes ours without labour works of labour not our own. The envious are therefore to be told that, when they fail to keep themselves from spite, they are being sunk into the old wickedness of the wily foe. For of him it is written, But by envy of the devil death entered into the world. For, because he had himself lost heaven, he envied it to created man, and, being himself ruined, by ruining others he heaped up his own damnation. The envious are to be admonished, that they may learn to how great slips of ruin growing under them they are liable; since, while they cast not forth spite out of their heart, they are slipping down to open wickedness of deeds. For, unless Cain had envied the accepted sacrifice of his brother, he would never have come to taking away his life. Whence it is written, And the Lord had respect unto Abel and to his offering, but unto Cain and to his offering He had not respect. And Cain was very angry, and his countenance fell. Thus spite on account of the sacrifice was the seed-plot of fratricide. For him whose being better than himself vexed him he cut off from being at all. The envious are to be told that, while they consume themselves with this inward plague, they destroy whatever good they seem to have within them. Whence it is written, Soundness of heart is the life of the flesh, but envy the rottenness of the bones. For what is signified by the flesh but certain weak and tender actions, and what by the bones but brave ones? And for the most part it comes to pass that some, with innocence of heart, in some of their actions seem weak; but others, though performing some stout deeds before human eyes, still pine away inwardly with the pestilence of envy towards what is good in others. Wherefore it is well said, Soundness of heart is the life of the flesh; because, if innocence of mind is kept, even such things as are weak outwardly are in time strengthened. And rightly it is there added, Envy is the rottenness of the bones; because through the vice of spite what seems strong to human eyes perishes in the eyes of God. For the rotting of the bones through envy means that certain even strong things utterly perish.
Source: Pastoral Rule (New Advent)