Excerpt arguing that ambition, not poverty, makes people unhappy

Those greedy for riches are ever discontented with their estate. When you are born in poverty, what need have you to wish yourself wealthy? Is it not better to sleep on felt and be in health than on down and be sick? Is it not better to wish to preserve tranquillity of spirit in a moderate condition than to grieve and be troubled amid a superfluity of possessions? It is not poverty that makes us unhappy, but ambition and vanity. Riches will by no means deliver you from fear; reason alone can accomplish that: and consequently he who enriches his reason is ever content with himself and never complains of poverty