A thankful heart is not only the greatest virtue, but the parent of all the other virtues.

The saying frames gratitude as both a supreme moral excellence and a generative force: a “thankful heart” disposes a person toward humility, fairness, and benevolence, making other virtues easier to practice and sustain. It also implies a social ethic—gratitude acknowledges dependence on others and on fortune, countering entitlement and resentment. In a Ciceronian key, the thought aligns with Roman ideals of reciprocal obligation (beneficium and gratia), where recognizing benefits received helps maintain civic friendship and moral duty. Even if the exact wording is later, the idea resonates with classical moral philosophy’s view that inner dispositions shape outward ethical conduct.