By the time of Aquinas the necessity of commerce had come to be fully realised, as appears from the passage in the _De Regimine Principum_: 'There are two ways in which it is possible to increase the affluence of any State. One, which is the more worthy way, is on account of the fertility of the country producing an abundance of all things which are necessary for human life, the other is through the employment of commerce, through which the necessaries of life are brought from different places. The former method can be clearly shown to be the more desirable.... It is more admirable that a State should possess an abundance of riches from its own soil than through commerce. For the State which needs a number of merchants to maintain its subsistence is liable to be injured in war through a shortage of food if communications are in any way impeded. Moreover, the influx of strangers corrupts the morals of many of the citizens... whereas, if the citizens themselves devote themselves to commerce, a door is opened to many vices. For when the desire of merchants is inclined greatly to gain, cupidity is aroused in the hearts of many citizens.... For the pursuit of a merchant is as contrary as possible to military exertion. For merchants abstain from labours, and while they enjoy the good things of life, they become soft in mind and their bodies are rendered weak and unsuitable for military exercises.... It therefore behoves the perfect State to make a moderate use of commerce.'[1] [Footnote 1: ii. 3.]