Will and Ariel Durant dedicated their lives to writing a history of the world that spans 11 volumes, 10K pages, and 4M words. Then they summarized the whole thing in the 128-page Lessons of History, which was published in 1968. I'm not sure such a book could be published today, because some of the ideas in it are... well, you'll see. Here are a few passages that I found thought-provoking. As always, don't take these as an endorsement. Read the book and form your own opinions.

On inequality and the concentration of wealth:

Inequality is not only natural and inborn, it grows with the complexity of civilization. Hereditary inequalities breed social and artificial inequalities; every invention or discovery is made or seized by the exceptional individual, and makes the strong stronger, the weak relatively weaker, than before. (chapter 3)

Nature smiles at the union of freedom and equality in our utopias. For freedom and equality are sworn and everlasting enemies, and when one prevails the other dies. Leave men free, and their natural inequalities will multiply almost geometrically, as in England and America in the nineteenth century under laissez-faire. To check the growth of inequality, liberty must be sacrificed, as in Russia after 1917. Even when repressed, inequality grows; only the man who is below the average in economic ability desires equality; those who are conscious of superior ability desire freedom; and in the end superior ability has its way. Utopias of equality are biologically doomed, and the best that the amiable philosopher can hope for is an approximate equality of legal justice and educational opportunity. A society in which all potential abilities are allowed to develop and function will have a survival advantage in the competition of groups. (chapter 3)

On long-term economic cycles:

Every economic system must sooner or later rely upon some form of the profit motive to stir individuals and groups to productivity. Substitutes like slavery, police supervision, or ideological enthusiasm prove too unproductive, too expensive, or too transient. (chapter 8)

Since practical ability differs from person to person, the majority of such abilities, in nearly all societies, is gathered in a minority of men. The concentration of wealth is a natural result of this concentration of ability, and regularly recurs in history. [...] The concentration [of wealth] may reach a point where the strength of number in the many poor rivals the strength of ability in the few rich; then the unstable equilibrium generates a critical situation, which history has diversely met by legislation redistributing wealth or by revolution distributing poverty. (chapter 8)

On governments and revolutions:

Nothing is clearer in history than the adoption by successful rebels of the methods they were accustomed to condemn in the forces they deposed. (chapter 5)

No one man, however brilliant or well-informed, can come in one lifetime to such fullness of understanding as to safely judge and dismiss the customs or institutions of his society, for these are the wisdom of generations after centuries of experiment in the laboratory of history. (chapter 5)

Most governments have been oligarchies -- ruled by a minority, chosen either by birth, as in aristocracies, or by a religious organization, as in theocracies, or by wealth, as in democracies. [...] If the majority of abilities is contained in a minority of men, minority government is as inevitable as the concentration of wealth; the majority can do no more than periodically throw out one minority and set up another. (chapter 10)

Democracy is the most difficult of all forms of government, since it requires the widest spread of intelligence, and we forgot to make ourselves intelligent when we made ourselves sovereign. (chapter 10)