There is an interesting passage in the writings of Valerius Maximus (III.3) that is open to different interpretations. It reads as follows:
Virtue is not exacting in her admittance. She allows personalities with vibrant lives to appear before her, and presents them with a taste of her offerings that, with regard to distinction between people, is neither lavish nor stingy. She is open to everyone on an equal basis, and evaluates the desire you carry with you more than your social status. In taking a quantity of her good offerings, she leaves the final weight for you yourself to calculate, so that the quantity you carry away with you is what your spirit is able to bear. So it happens that persons born to lowly stations may surge to the highest pinnacle of status, and conversely, the brood of the most distinguished figures may collapse into dishonor, converting the brilliant light they inherited from their ancestors into a shameful gloom.
What exactly is Valerius speaking of here? Is he trying to make the point that the “quantity of virtue” must be left to each person to decide? Or is he trying to point out the intersection of virtue with fortune, reminding us that persons of humble origin can rise to the peak of success, while the scions of noble families can collapse into disgrace and ruin? It seems to me that he wants us to appreciate a certain truth before anything else: that virtue is open to all without preconditions. Anyone can gain admittance to virtue’s court; the lowliest urchin is on equal ground with the most distinguished notable.
Once admittance is granted, virtue becomes an evaluator: she will assess what level of desire you carry with you for her offerings. Some are eager to take them from virtue’s outstretched hand; others are just going through the motions, while preserving a sterile aversion in their hearts for anything righteous or sublime. It is you, the seeker, who must determine how much of her offerings you can carry with you. And in this regard we may call attention to the capacity of the soul for virtue; a great and capacious soul, one that is expansive in greatness, will be far better suited to bear a virtuous freight than a stingy, small, shriveled soul. Each man will decide for himself, for every man knows in his heart how much he can carry. In this regard the Stoics were wrong to adhere to the rigid position that a man was either virtuous, or he was not; it is more accurate to say that there are great differences in the quantities of virtue that men can carry.
And this is why, as Valerius notes, the humble can be raised to the skies, while the high-bred can fall precipitously into the chasms of corruption and ruin. The difference lies in the capacity of the soul; some can carry much, and can survive a prolonged trek into life’s deserts or mountainous regions. Others can bear but little; and once these supplies are exhausted, they are no longer able to continue.
Elsewhere Valerius relates (III.2) the tale of a brave princess named Harmonia, who was daughter to Gelon I, a fifth-century king of the city of Syracuse. Civil strife was abroad in the land, and hostile mobs were preparing to storm the royal residence. One of the nurses at court decided to protect Harmonia by arranging for what we would call a “body double”; she had a servant girl who resembled Harmonia dressed up in royal raiment so that intruders would think she was the princess. When assassins finally did come, they seized the body-double, and began to torment and abuse her. Knives then came out, and she was physically attacked; yet she, a loyal subject, never uttered one word, and never revealed that she was not the real Harmonia. When Harmonia heard of this heroism, she was so moved that she could not bear to continue living with the knowledge of her servant’s nobility of soul. So she confronted the mob herself, and declared who she was, and willingly offered herself up as a sacrifice. And so it was, as Valerius beautifully says,
So the end of life was an edifice of falsity for one, and an exposed truth to another. 
Both of these deaths were heroic, and Valerius means nothing derogatory by calling the servant’s death the result of an “edifice of falsity”; he is only trying to make that point that the two girls met the same end through different assertions. The capacity of their souls remained equal in the event.
And the capacity of the soul can change over time. He who may once have been noble, may one day find himself subject to the temptations of corruption. For it seems to me that souls, like the words of a language, exist as a result of only two processes: coinage (inventio) or divergence (declinatio). The writer Varro, I believe, made this point (or one similar to it) when he was speaking of the origin of words in the Latin language. What I mean here is that the condition of souls can be evaluated from the perspective of their original creation, or from examining the gradual process of divergence (evolution) from their original state. We are all subject to gradual decay and corruption. It is difficult not to conclude that there is at least some truth in the historian Florus’s declaration (II.13) about the assassination of Julius Caesar:
Thus he who had filled the entire world with the blood of his citizens at last filled the Curia with his own blood. 
What one does repeatedly to others, may eventually be done to him too; for the scales of fate aim for a cosmic balancing of deeds and morals. Caesar was a great man, certainly “the most complete man that antiquity produced,” in the words of Will Durant; and yet even the greatest of men can overreach, and forget the meaning of restraint. The quantity of virtue that we seek to know, and to incorporate into our constitutions, is something that each person must decide for himself. The quantity that we carry is whatever our spirit can bear. And this is why a capacious spirit, a capacious soul, is so vital: it is another reminder of the critical importance of Cicero’s concept of magnitudo animi, or greatness of soul, that we encountered in his On Moral Ends and On Duties.
The more acute our vision becomes, the more we see that the truest things in philosophy all begin to reference each other.
 Ita alteri tectum mendacium, alteri veritas aperta finis vitae fuit.
 Sic ille qui terrarum orbem civili sanguine impleverat, tandem ipse sanguine suo curiam implevit.
Read more in On Moral Ends: