Aristotle wrote about poverty and wealth in a scattered way in The Nicomachean Ethics.
Here are some excerpts:
Everyone equates living well and being successful with being happy. But as to the nature of happiness, there is no agreement, and the correction of the crowd do not resemble those of the wise. Some, in fact, identify happiness with something apparent and visible, like pleasure, wealth or honor. For some it is one thing, and for other another. Often the same man changes his mind about it: sick, he places happiness in health, and poor, in wealth.
Aristotle, Nicomachean Ethics, Chapter 2
To the question, what is a successful life? Aristotle in this excerpt states that everyone will surely answer being happy.
But the real question is what is happiness? For some, it is having goods, such as wealth.
It is when one is poor that one believes that happiness is to be rich.
As for the action of giving and that of acquiring wealth, the right balance is liberality; the excess and the defect is respectively prodigality and parsimony. It is in the opposite way that in these actions one falls into excess or defect: indeed, the prodigal sins by excess in spending and by defect in acquiring, while the parsimonious sins by excess in acquiring and by defect in spending.
Aristotle, Nicomachean Ethics, Chapter 7
Aristotle establishes the two extremes in terms of poverty and wealth: profligacy, on the one hand, and parsimony on the other. Of course, one must find the right balance.
As for poverty, we should probably not fear it, nor disease, nor in general any of the evils that do not come from a vice or that are not due to the agent himself. But he who has no fear of them is not a brave man either (though we apply this qualification to him also by similitude), for some men, who are cowardly in the dangers of war, are not less liberal in nature in matters of money, and bear with constancy the loss of their fortune. Nor is one a coward if one dreads the insult to one’s children and wife, or envy or some such evil; nor is one brave if one shows the heart at the moment of receiving the whip.
Aristotle, Nicomachean Ethics, Chapter 9
One should not be afraid of poverty. But he who is not afraid of poverty, for all that, cannot be considered brave.
In theNicomachean Ethics, Aristotle explains further:
The more glaring the inequalities is with a very rich class and a very poor class, the more the political situation is endangered. To have a certain stability of the state, it is better to have a very large middle class.
→ Summary of the Wealth of Nations – Adam Smith