Lactantius — Divine Institutes 5.7
But God, as a most indulgent parent, as the last time approached, sent a messenger who would bring back that old age and the justice that had fled, lest the human race be driven by the greatest and perpetual errors. So the appearance of that golden time returned, and justice was indeed restored to the earth, but assigned to a few--and justice is nothing other than the pious and religious cult of the one God.
But someone may perhaps be moved: why, if this is justice, was it not given to the whole human race, and why has the universal multitude not agreed on it? This is a large dispute--why, when God gave justice to the earth, diversity was kept--which I have declared elsewhere and will explain wherever it fits. For now it is enough to mark briefly that virtue either cannot be seen unless it has contrary vices, or is not perfect unless it is exercised by adversities. God willed there to be this distance of goods and evils, so that we may know the quality of the good from the evil, and likewise of the evil from the good; and the account of either cannot be understood if the other is removed. God therefore did not shut out evil, so that the account of virtue could stand. How would patience keep its force and name if there were nothing we were forced to suffer? How would faith devoted to its God earn praise unless there were someone who wanted to turn people away from God? For that reason he allowed the unjust to be more powerful, so they could compel toward evil, and more numerous, so that virtue would be precious because it is rare.
This of course is the cause why, although justice has been sent to humans, a golden age is still not said to be: because he did not remove evil, so that he might keep the diversity which alone contains the sacrament of divine religion.
Latin
Sed deus ut parens indulgentissimus adpropinquante ultimo tempore nuntium misit, qui uetus illut saeculum fugatamque iustitiam reduceret, ne humanum genus maximis et perpetuis agitaretur erroribus. rediit ergo species illius aurei temporis et reddita quidem terrae, sed paucis adsignata iustitia est, quae nihil aliut est quam dei unici pia et religiosa cultura.
sed moueat aliquem fortasse, cur si haec sit iustitia, non omni humano generi sit data nec in eam multitudo uniuersa consenserit. magnae hoc disputationis est, cur a deo, cum iustitiam terrae daret, sit retenta diuersitas: quod et alio loco declaraui et ubicumque opportune inciderit explicabitur. nunc designare id breuissime satis est, uirtutem aut cerni non posse, nisi habeat uitia contraria, aut non esse perfectam, nisi exerceatur aduersis. hanc enim deus bonorum ac malorum uoluit esse distantiam, ut qualitatem boni ex malo sciamus, item mali ex bono: nec alterius ratio intellegi sublato altero potest. deus ergo non exclusit malum, ut ratio uirtutis constare posset. quomodo enim patientia uim suam nomenque retineret, si nihil esset quod pati cogeremur? quomodo laudem mereretur deuota deo suo fides, nisi esset aliquis qui a deo uellet auertere? nam ideo potentiores esse iniustos permisit, ut cogere ad malum possent, ideo plures, ut uirtus esset pretiosa, quod rara est. quod quidem ipsum Quintilianus egregie ac breuiter ostendit in Capite obuoluto. nam quae inquit uirtus esset innocentia, nisi laudem raritas dedisset? uerum quia natura sic conparatum est, ut odium cupiditas ira in id quod incubuerunt agant caecos, supra hominem uidetur culpa uacare. alioquin si natura pares omnibus adfectus dedisset, pietas nihil erat. hoc quam uerum sit, docet necessitas ipsa rationis. si enim uirtus est malis ac uitiis fortiter repugnare, apparet sine malo ac uitio nullam esse uirtutem. quam deus ut absolutam perfectamque redderet, retinuit id quod erat ei contrarium, cum quo depugnare posset: agitata enim malis quatientibus stabilitatem capit et quanto frequenter inpellitur, tanto firmiter roboratur.
haec nimirum causa efficit ut quamuis sit hominibus missa iustitia, tamen aureum saeculum non esse dicatur, quia malum non sustulit, ut retineret diuersitatem, quae sacramentum diuinae religionis continet sola.