Lactantius, Divine Institutes 6.11
We must preserve our humanity if we wish to be called human beings in the true sense. And what is preserving humanity but loving a person simply because he is a person, the same as we are? Discord and dissension are therefore contrary to human reason, while the truth lies in Cicero's statement: a man who obeys nature cannot harm another man. Since harming a man is against nature, benefiting him must necessarily be according to nature. Anyone who fails to do this strips himself of the name of man, for the duty of humanity is to come to the aid of human need and danger. I therefore ask those who claim it is not wise to be moved or to show pity: if a man seized by a wild beast begs an armed man for help, do they think he ought to be helped or not? They are not so shameless as to deny that what humanity demands must be done. Likewise, if someone is surrounded by fire, crushed by a collapsing building, drowning in the sea, or swept away by a river, do they think it is not a man's duty to help? Let them not call themselves men if they think so — for no one is immune to such dangers — but rather they will admit it is the duty of a man, and of a strong man, to save one who is perishing. If they concede that in such cases, because they bring danger to life, it is humanity's duty to help, what reason can they give for refusing to help when a man is hungry, thirsty, or cold? These conditions are equal in nature to those chance events and call for the same humanity, yet they draw a distinction between them, because they measure everything not by the truth of the matter itself but by present utility. They hope that those they rescue from danger will return gratitude, but since they expect no return from the needy, they consider whatever they give to such people lost. From this comes that detestable saying of Plautus: "He deserves ill who gives a beggar food to eat, for both the gift perishes and he prolongs the beggar's life in misery." But perhaps the poet was speaking in character.
Latin
Conseruanda est igitur humanitas, si homines recte dici uelimus. id autem ipsum, conseruare humanitatem, quid aliut est quam diligere hominem, quia homo sit et idem quod nos sumus? -discordia igitur ac dissensio non est secundum hominis rationem uerumque illut est Ciceronis, quod ait hominem naturae oboedientem homini nocere non posse. ergo si nocere homini contra naturam est, prodesse igitur homini secundum naturam sit necesse est. quod qui non facit, hominis se appellatione despoliat, quia humanitatis officium est necessitati hominis ac periculo subuenire. quaero igitur ab iis qui flecti et misereri non putant esse sapientis, si homo ab aliqua bestia conprehensus auxilium sibi armati hominis inploret, utrumne succurrendum putent an minime. non sunt tam inpudentes, ut negent fieri oportere quod flagitat, quod exposcit humanitas. item, si aliquis circumueniatur igni, ruina opprimatur, mergatur mari, flumine rapiatur, num putent hominis esse non auxiliari. non sint ipsi homines, si putent — nemo enim potest eiusmodi periculis non esse subiectus —, immo uero et hominis et fortis uiri esse dicent seruare periturum. si ergo in eiusmodi casibus, quia periculum uitae homini adferunt, succurrere humanitatis esse concedunt, quid causae est cur, si homo esuriat sitiat algeat, succurrendum esse non putent? quae cum sint paria natura cum illis casibus fortuitis et unam eandemque humanitatem desiderent, tamen illa discernunt, quia non re ipsa uera, sed utilitate praesenti omnia metiuntur. illos enim quos periculo subripiunt sperant sibi gratiam relaturos, egentes autem quia non sperant, perire arbitrantur quidquid eiusmodi hominibus inpertiant. hinc est illa Plauti detestanda sententia: male meretur qui mendico dat quod edat: nam et illut quod dat perit et illi producit uitam ad miseriam. at enim poeta fortasse pro persona locutus est.