When the Law says, "You shall not covet," these words mean that we should banish our desires for whatever does not belong to us. Our thirst for another's goods is immense, infinite, never quenched. Thus it is written: "He who loves money never has money enough." 320
Catechism number 2537
It is not a violation of this commandment to desire to obtain things that belong to one's neighbor, provided this is done by just means. Traditional catechesis realistically mentions "those who have a harder struggle against their criminal desires" and so who "must be urged the more to keep this commandment":
. . . merchants who desire scarcity and rising prices, who cannot bear not to be the only ones buying and selling so that they themselves can sell more dearly and buy more cheaply; those who hope that their peers will be impoverished, in order to realize a profit either by selling to them or buying from them . . . physicians who wish disease to spread; lawyers who are eager for many important cases and trials.321