He is richest who is content with the least, for content is the wealth of nature.
Socrates isn't simply telling us that wanting less brings peace—he's making a bolder claim about the nature of wealth itself, suggesting that our measure of riches has been fundamentally backwards. The word "nature" here is doing heavy lifting: he means that contentment isn't a mere feeling we manufacture through discipline, but rather an alignment with how things actually are, which is why it's described as nature's own wealth. A person earning forty thousand dollars who frets over what neighbors possess experiences genuine poverty, while someone living on half that with a satisfied mind possesses genuine richness—and this isn't motivational thinking but observable fact. The insight cuts against our instinct to solve unhappiness by acquiring more, when the solution was available all along through a different relationship with what we already have.