90 There are those who humble themselves in abundance of riches, and they act rightly and prudently, for the law of nature is sufficiently rich for all, according to which one may soon find what is more than enough; but for lust any abundance of riches is still penury. Again, no one is born poor but becomes so. Poverty then is not in nature but in our own feelings, and so to find oneself rich is easy for nature, but hard for lust. For the more a man has gained the more he thirsts for gain, and burns as it were with a kind of intoxication from his lusts.
Source: Letters (New Advent)