Since law constitutes the bond of civil society, and the authority of the law is equal, how can the society of citizens be maintained when their condition is not equal? If it be not pleasing to place their wealth on equal footing, and if everyone is endowed with unequal abilities, certainly all of those who are citizens of the same republic ought to have equal rights. For, what is the state but the shared rights of its citizens?

[Quare cum lex sit civilis societatis vinculum, ius autem legis aequale, quo iure societas civium teneri potest, cum par non sit condicio civium? Si enim pecunias aequari non placet, si ingenia omnium paria esse non possunt, iura certe paria debent esse eorum inter se, qui sunt cives in eadem re publica. Quid est enim civitas nisi iuris societas?]

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

De Re Publica [On the Republic, On the Commonwealth], Book 1, ch. 32 / sec. 49 (1.49) (54-51 BC) [tr. @sentantiq (2017)]
    (Source)

(Source (Latin)). Alternate translations:

Wherefore as the law is the bond of civil society, and equal rights form that of the law, by what power can a community of citizens be maintained, where their condition is not an equal one? If therefore it is not expedient to equalize fortunes; if the powers of mind cannot be equalized in all, certainly then an equality of rights ought to exist, among those who are citizens of the same republic. For what is a state but a community of rights?
[tr. Featherstonhaugh (1829)]

Wherefore, since the law is the bond of civil society, and the justice of the law equal, by what rule can the association of citizens be held together, if the condition of the citizens be not equal? For if the fortunes of men cannot be reduced to this equality—if genius cannot be equally the property of all—rights, at least, should be equal among those who are citizens of the same republic. For what is a republic but an association of rights?
[tr. Barham (1841)]

Wherefore, since the law is the bond of civil society, and the justice of the law equal, by what rule can the association of citizens be held together, if the condition of the citizens be not equal? For if the fortunes of men cannot be reduced to this equality -- if genius cannot be equally the property of all -- rights, at least, should be equal among those who are citizens of the same republic. For what is a republic but an association of rights?
[tr. Yonge (1853)]

Therefore, since law is the bond which unites the civic association, and the justice enforced by law is the same for all, by what justice can an association of citizens be held together when there is no equality among the citizens? For if we cannot agree to equalize men’s wealth, and equality of innate ability is impossible, the legal rights at least of those who are citizens of the same commonwealth ought to be equal. For what is a State except an association or partnership in justice?
[tr. Keyes (1928)]

Since, then, law is the bond that holds political society together, and since equality of rights is a part of law, by what principle of right can an association of citizens be held together, when the status of these citizens is not equal? For, if it is not thought desirable that property should be equally distributed, and if the natural capacities of all men cannot possibly be equal, yet certainly all who are citizens of the same commonwealth ought to enjoy equal rights in their mutual relations. What, indeed, is a state, if it is not an association of citizens united by law?
[tr. Sabine/Smith (1929)]

Since, then, law is the bond which holds together a community of citizens, and the justice embodied in the law is the same for everyone, by what right can a community of citizens be held together when their status is unequal? If the equalization of wealth is rejected, and the equalization of everybody’s abilities is impossible, legal rights at least must be equal among those who live as fellow-citizens in the same state. For what is a state other than an equal partnership in justice?
[tr. Rudd (1998)]

And therefore, since law is the bond of civil society, and rights under law are equal, then by what right can a society of citizens be held together when the status of citizens is not the same? Even if equality of property is not appealing, and if the mental abilities of all cannot be equal, certainly the rights of all who are citizens of the same commonwealth ought to be equal. What is a state if not the association of citizens under the law?
[tr. Zetzel (1999)]