Gregory the Great
Catena Aurea · Matthäusevangelium 5
Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you and persecute you; That ye may be the children of your Father which is in heaven: for He maketh His sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust. For if ye love them which love you, what reward have ye? do not even the Publicans the same? And if ye salute your brethren only, what do ye more than others? do not even the Publicans so? Be ye therefore perfect, even as your Father which is in heaven is perfect.
(Mor. xxii. 11.) Love to an enemy is then observed when we are not sorrowful at his success, or rejoice in his fall. We hate him whom we wish not to be bettered, and pursue with ill-wishes the prosperity of the man in whose fall we rejoice. Yet it may often happen that without any sacrifice of charity, the fall of an enemy may gladden us, and again his exaltation make us sorrowful without any suspicion of envy; when, namely, by his fall any deserving man is raised up, or by his success any undeservedly depressed. But herein a strict measure of discernment must be observed, lest in following out our own hates, we hide it from ourselves under the specious pretence of others’ benefit. We should balance how much we owe to the fall of the sinner, how much to the justice of the Judge. For when the Almighty has struck any hardened sinner, we must at once magnify His justice as Judge, and feel with the other’s suffering who perishes.