But if nature does not ratify law, then all the virtues may lose their sway. For what becomes of generosity, patriotism, or friendship? Where will the desire of benefitting our neighbours, or the gratitude that acknowledges kindness, be able to exist at all? For all these virtues proceed from our natural inclination to love mankind.

[Atqui si natura confirmatura ius non erit, uirtutes omnes tollantur. Vbi enim liberalitas, ubi patriae caritas, ubi pietas, ubi aut bene merendi de altero aut referendae gratiae uoluntas poterit existere? Nam haec nascuntur ex eo quod natura propensi sumus ad diligendos homines, quod fundamentum iuris est.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

De Legibus [On the Laws], Book 1, ch. 15 / sec. 43 (1.15/1.43) [Marcus] (c. 51 BC) [tr. Barham/Yonge (1878)]
    (Source)

(Source (Latin)). Alternate translations:

If nature does not ratify law, all the virtues lose their sway. What becomes of generosity, patriotism, or friendship? Where should we find the desire of benefitting our neighbours, or the gratitude that acknowledges kindness? For all these virtues proceed from our natural inclination to love and cherish our associates.
[tr. Barham (1842)]

And if Nature is not to be considered the foundation of Justice, that will mean the destruction [of the virtues on which human society depends]. For where then will there be a place for generosity, or love of country, or loyalty, or the inclination to be of service to others, or to show gratitude for favours received? For these virtues originate in our natural inclination to love our fellow-men, and this is the foundation of Justice.
[tr. Keyes (1928)]

That is why every virtue is abolished if nature is not going to support justice. What room will there be for liberality, patriotism, and devotion; or for the wish to serve others or to show gratitude? These virtues are rooted in the fact that we are inclined by nature to have a regard for others; and that is the basis of justice.
[tr. Rudd (1998)]

If nature will not confirm justice, all the virtues will be eliminated. Where will there be a place for liberality, for love of country, for piety, for the desire to do well by others or return kindness? These all arise because we are inclined by nature to love other humans, and that is the foundation of justice.
[tr. Zetzel (1999)]

And if right has not been confirmed by nature, they may be eliminated. In fact, where will liberality be able to exist, where affection for the fatherland, where piety, where the will either to deserve well of another or to or to return a service? These things originate in this, that we are inclined by nature to to cherish human beings; that is the foundation of right.
[tr. Fott (2013)]