Do good to thy friend to keep him, to thy enemy to gain him.
Franklin presents kindness as useful in both friendship and conflict. Doing good to a friend helps preserve trust, affection and mutual loyalty. The same behaviour towards an enemy can serve a different purpose: it may reduce hostility, challenge negative assumptions and create an opportunity for reconciliation.
The saying therefore treats generosity not only as a moral virtue but also as a practical way of shaping relationships. Retaliating against hostility can deepen conflict, while goodwill may make cooperation possible where none existed before. Franklin does not suggest that every enemy will become a friend, or that harmful behaviour should simply be tolerated. Rather, the quotation argues that constructive treatment of others can strengthen existing bonds and sometimes transform adversarial ones. Its broader lesson is that goodwill can be more effective than resentment in both maintaining friendship and resolving conflict.