Rich and poor have been with us since time immemorial, and in saying "the poor you have always" (Mark 14:7), our Lord teaches that some poverty is inevitable as long as we live in this fallen world. Thus the Church has taught that "the world will never be able to rid itself of misery, sorrow and tribulation, which are the portion even of those who seem most prosperous" ; total equity, perfect justice and universal prosperity and goodness are only to be found in that kingdom which is to come, and for this reason, political or economic schemes which promise universal equality and a return to Eden in this temporal world are illusory. The best that can be accomplished in this fallen world is to mitigate the extremes to which poverty and wealth can tend towards.
On the one hand, poverty is mitigated by the presence of Christians in the world who give to the poor as if they were Christ Himself, remembering that "not to enable the poor to share in our goods is to steal from them" , and that our Lord demonstrated a special love for the poor and condemned immoderate love of riches as incompatible with the kingdom of heaven. The history of the Catholic Church serves innumerable examples of ways in which the poor have been cared for by the Church; no institution has fed, clothed, or educated more people than the Catholic Church.
But we also mentioned above that not only is the sharp edge of poverty mitigated, but also the immoderate excesses towards which excessive wealth can tend. While poverty can degrade a man, the power and prestige that wealth brings can puff him up with pride and cause him to become a burden and a terror to his fellow men, lording it over them and using his wealth to increase his own power rather than to benefit humanity. Identifying this danger is not unique to Christianity; wherever in human history wealthy lords and elites have used their riches to oppress others, the cry of the poor has gone up to heaven.
The Problem of Inequality
This is true in our own day and age as well, although our time is unique in that, while there is still a universal understanding that the poor need to be helped, by and large western society has abandoned the notion that immoderate accumulation of wealth is also a problem. Sure, textbooks and a few lone prophets warn us that a situation in which 10% of the population owns 80% of the wealth is inherently dangerous, but by and large the people of the west either don't care about this radical inequality, or what's worse, perhaps defend this massive centralization of wealth in a few hands as a positive good . Some admit it is a problem, but lament that there is nothing that can be done about it.
There is, of course, the solution that is posited by the socialists: simply take the wealth away from the rich in the form of taxation, put all of this money into the hands of the government, and then allow the government a massive expansion of power to redistribute this wealth as it sees fit. This solution is extremely problematic for many reasons and cannot be condoned by any Catholic. Thus Pius XI wrote, "No one can be at the same time a good Catholic and a true socialist" . Socialism subordinates man to the state, seeks to eliminate the abuses of private property by eliminating private property rather than the abuses, and promotes a kind of worldly utopian vision that the Church has always condemned. It affirms subsidiarity at the private level while allowing massive accumulation of power at the government level.
The fact that socialism is not an answer has led many to lament that the inequality problem cannot be solved, that the outrageous power wielded by the rich in a capitalist society is just a necessary evil of the system that has to be tolerated - that this inequality is the sharp edge of capitalism that cannot be dulled.
Historical Perspectives: The Greek Liturgy
The purpose of this essay is not to propose concrete solutions to the modern problems of wealth disparity, but rather to look at historical examples of how this disparity has been addressed by other cultures historically, both pagan and Christian. These examples are notable because, while they may not be directly applicable to our current situation, they show how solutions have indeed been posited that fall far outside the false capitalism-or-socialism dichotomy.
Let us begin with ancient Greece. The ancient Greek world was notable for its social inequality. In the cradle of democracy, citizens of the polis had numerous rights denied to the vast majority of non-citizens and slaves. Power and wealth usually went hand in hand. Yet for a people who cared so much about liberty and freedom as the ancient Greeks, it is to be expected that the wealth and privileges enjoyed by some did not come without strings attached. The wealthy in ancient Greece, especially Athens, were mandated by law to pay for the upkeep of certain public works. These works financed by the rich were called liturgies, understood in its original context as a work of or for the people.
Liturgies were distributed based on wealth; extremely rich citizens might have to fund triremes or pay for the upkeep of construction of public buildings; the maintenance of roads was another common liturgy, as was the building of bridges and the funding of religious festivals. Participation in these liturgies was mandatory; the rich who participated were not viewed as making charitable contributions, but as performing obligatory duties to the state for the common good. In this manner, the local governments obtained a reliable source of funding for important projects and found a way to direct the wealth of the rich towards the common good. The rich, for their part, were allowed to take credit for the projects, which were often named after them or for which they received public accolades, which were helpful for political advancement. For this reason, many of the rich voluntarily went beyond what the law required: When one Lysias was defending himself before a court on various charges, he presented a list of the liturgies he had participated in, noting how he had done more than the letter of the law required and stated, "If I wanted to do the minimum the law required, I would not have even made a quarter of these expenditures...this is indeed how I treat the city: in my private life I'm thrifty, but in public office I gladly pay, and I am proud not of the property I have left, but of the spending that I made for you " 
The Patron-Client System of Rome
Moving from Greece to Rome, we see income disparity at even higher levels. As the Roman Republic spread outside the boundaries of Italy and began gobbling up large portions of the Mediterranean world, the Roman upper classes accumulated so much land and wealth that the majority of Italian land and capital was in the hands of a tiny elite. Though legal attempts to redress this inequality would ultimately fail, Roman culture had an inherent mechanism for ensuring that the wealth of the rich was not simply hoarded, but returned in part to the community. This was through the patron-client system.
Under the patron-client system, wealthy and powerful families took lesser families and individuals under their patronage. The client families were expected to support their patrons politically, to do work for them at times, and offer their assistance in court. The patron had mutual obligations to the client; he was expected to help advance the client's political or professional career, testify on his behalf in court, help him arrange business deals or marriages, loan him money if needed, and in certain circumstances, provide financially for a client's widows or children in the event of disaster. The wealthy had a personal obligation to use his position and prestige to benefit those who were not as well off.
As in Greece, this was not seen as an act of charity but of obligation. The patron-client system was very ancient and established in "ancestral customer" (mos mairoum); the fundamental disposition of the client was one of pietas, faithfulness or devotion, while the disposition of the patron towards his client was one of fides, understood as steadfastness, or reliability. While there were certain laws governing the relationship of patrons and clients (they could not sue one another, for example, and a freed slave automatically became the client of his former master), the relationship was mostly enforced by custom and the strictness of public opinion. A patron who left his clients destitute or refused to look after them was looked upon very poorly and greatly diminished his prestige. Thus, the power of custom and law coalesced to compel the rich and powerful to redirect a portion of their wealth and authority in order to benefit the others. Presupposing this system was the idea that great wealth and great obligation went together.
Vassalage and Patronage in Medieval Europe
There have been volumes of research written on the potential relationship between the Roman patron-client system and the medieval vassalage system; to what degree did the former evolve into the latter? This question, however interesting, does not concern us here. We are interested rather in the manner in which medieval concepts of patronage served to use social or legal pressure to redirect the wealth of the rich from private to public purposes.
Medieval lords saw themselves as bound to serve their vassals in the sense that they protected them physically, but in reality the lord's involvement in the affairs of his vassals was sometimes minimal, and often parasitical. If we are to look for the way that patronage influenced distribution of wealth in medieval Europe, we should look not to the relation between lords and peasants, but between lords and the Church, where the patronage was much more established by social custom and is easier to document.
While a lord was not necessarily recognized as master of the Church in his domain (at least after the 11th century), it was always understood that one of the duties of the peerage was to see to the spiritual welfare of one's people. In later centuries this meant the lord using the law to enforce doctrinal orthodoxy, but in the early Middle Ages it meant primarily using his personal funds to endow monasteries and churches. We are quick to admire the beauty of the abbeys and cathedrals of medieval Europe, but we often forget that by and large these edifices were financed by wealthy laymen who were putting their wealth at the service of the Church and their people.
A few examples:
The famous monastery of Cluny, which would become a center of monastic revival in the 11th century, was founded and endowed by Duke William I of Aquitaine. The land upon which the famous Cathedral of Canterbury was built was donated by King Ethelbert of Kent. King Edward the Confessor personally paid for the large parts of the construction of Westminster Abbey. These are well-known examples, but the endowment system was universal; every monastery needed a wealthy patron who would endow it and look after its temporal needs. Parishes were also endowed as well.
These endowments served to minister to the spiritual needs of the commoners, and often to their physical needs as well, since Catholic monasteries were sources of relief for the poor. Again, this was not seen as a charity on the part of the rich, but an obligation that came with their high office. Their wealth was not to be hoarded or squandered on selfish pursuits, but was rather to be put to the utility of the commoners and the salvation of souls. A ruler who failed to do this was strongly censured by the Church as stingy, avaricious, and uncaring; his immortal soul was in jeopardy. Again, we see social mores and popular custom pressuring the wealthy to put their private wealth to use for the public good as a matter of obligation. A good lord who gave his money for the use of the Church and the salvation of souls was doing the will of God proper to his station in life and could be assured of prayers for his soul by the communities he founded, both during and after the course of his earthly life.
The Modern Abandonment of the Idea
What are the common threads here? Though the practices we have examined are all different and divided by region, language, religion and time, there is a common assumption behind all of them: The assumption inequality in our temporal condition does not efface the brotherhood of all mankind; that the particular conglomerations of goods we see in our fallen world does not negate the universal destination of goods. By nature we are all brethren and inherently equal as men, a natural observation that even the pagans understood. It is only the chaos of living in a fallen world and the influence of original sin that has made some superiors over others, giving rise to social hierarchy. This social hierarchy is necessary in our world as part of the state, and is not inherently evil; even the heavens have a hierarchy - but the heavenly hierarchy is one of charity, not one of power and domination, which is why even though the world and the Church both have hierarchy, our Lord warns that the power structures in the Church are not to imitate those of the world: "The kings of the Gentiles lord it over them; and they that have power over them, are called beneficent.But you not so: but he that is the greater among you, let him become as the younger; and he that is the leader, as he that serves" (Luke 22:25-26). The poor we have with us always, but the peoples of the past constantly called to mind that the subjection of the poor to the mercies of the rich was not by nature, but by circumstance. They bore witness to this fundamental truth about humanity by compelling the rich, either by law or custom, to devote considerable amounts of their wealth to the public good, acknowledging the sharp inequality between rich and poor but using custom to dull the edge of the blade a bit by calling to mind the obligations that come with wealth - in Catholic language, to respect the universal destination of goods.
Then in the modern period, with the domination of laissez-faire thinking in economics, a fundamental shift happened in the way people thought about wealth and gain: instead of wealth as a means towards attaining the common good, the philosophy became what economic historian Robert Heilbroner has called "gain for the sake of gain"; gain detached from any useful purpose for which the accumulated wealth ought to be applied. 
In the modern economy, we can no longer speak of an "obligation" for the rich to put their money at the use of the community. Because gain for the sake of gain is good, the rich man is not told to howl and weep, as St. James admonishes (James 5:1), but is instead praised for mere fact of his wealth apart from the ends to which he puts it. The fact that the man has managed to accumulate wealth is a mark of success, and his right to enjoy it in any means he sees fit is sacrosanct. Thus it becomes a morally neutral question whether a rich man diverts his wealth towards funding a homeless shelter or accumulate a private collection of expensive cars beyond all possible utility. To speak of a man having any obligation, moral or legal, to "give back" to the community is taken as an endorsement of socialism and is akin to an accusation that the rich man did not get his wealth honestly.
Certainly, many rich people do choose to give back and endow or support many charitable causes. But in our current way of looking at things, this can only be viewed as charity and lauded as philanthropy; it is not viewed as the obligation of the rich man, what he is expected to do anyway, but as a charitable deed that he is going above and beyond in performing. Note that the presumption here is that the rich man has absolutely no obligation to devote any of his wealth to the public good; if an obligation did exist, then charitable actions of the wealthy would not be viewed as meritorious acts of philanthropy, but would just be viewed as what they were expected to due - their duty. The very fact that the rich are praised for philanthropy as an expression of charitable giving is a testament to the fact that our society has no concept of the wealthy having an obligation to help the common good, as did the traditional approaches to the question if disparity.
Did these traditional measures do away with poverty or the oppression of the rich? Of course not. We began this essay by noting that poverty could never ultimately be overcome in this world. But was society was better off with these customs in place than without them? Without a doubt. Even though neither the ancient, medieval or modern approach to the problem of income disparity was able to solve the problem, at least the ancient and medieval peoples did not celebrate it as the moderns do. The traditional practices were meant to ensure that the wealthy remembered that they were mere mortals, born into the world with their kinsmen and leaving it with nothing, and that wealth was basically a loan from the gods, fate, God, or whatever; the modern world celebrates gain for the sake of gain, encouraging massive centralization of wealth and power without responsibility, and the general public takes perverse enjoyment in watching the rich flaunt and squander their wealth in despicable reality television programming. The traditional practices at least were consonant with a Catholic anthropology that views wealth in terms of man's responsibility before God, to his fellow men, and calls to mind the universal destination of goods.
Can these solutions be implemented in the modern world? Should the rich be called upon to personally fund bridges and endow schools? Could poorer communities be put under the "patronage" of wealthy individuals or families, whose yearly income from interest sometimes exceeds the annual tax revenue of an entire city? I think we could not do anything like this without a fundamental shift in our attitudes towards wealth, which I do not see happening soon, since our current philosophy rewards greed and panders to man's lowest appetites. But I write not to propose any concrete solutions for our current predicament as much as use history to demonstrate that there have been other solutions in the past other than massive socialist redistribution schemes. If we can simply begin by thinking outside of the capitalist-socialist spectrum, we will have made considerable progress.
 Pius XI, Divini Redemptoris, 45
 St. John Chrysostom, Hom. in Lazaro 2,5
 Hurst, Charles E. (2007), Social Inequality: Forms, Causes, and Consequences, Pearson Education, Inc., p. 34
 Pius XI, Quadragesimo Anno, 120
 Lysias, XXI = Defending anonymous (5). Extract from the translation of Louis Gernet and Marcel Bizos.
 See Robert Heilbroner, The Worldly Philosophers