18. Crafts can improve and increase only when many
people demand them.
The 92 reason for this is that man cannot afford to give away his labor for nothing, because it is his (source of) profit and livelihood 93 Throughout his life, he has no advantage from anything else. Therefore, he must employ his labor only on whatever has value in his city, if it is to be profitable to him.
If a particular craft is in demand and there are buyers for it, (that) craft, then, corresponds to a type of goods that is in great demand and imported for sale. People in the towns, therefore, are eager to learn (that particular) craft, in order to make a living through it. On the other hand, if a particular craft is not in demand, there are no buyers for it, and no one is interested in learning it. As a result, (the craft) is destined to be left alone and disappears because of neglect.
Therefore, it has been said on the authority of 'Ali: "Every man's value consists in what he knows well." 94 This means that the craft he knows constitutes his value, that is, the value realized from his labor, which is his livelihood.
There is another secret to be understood in this connection. That is, that it is the ruling dynasty that demands crafts and their improvement. It causes the demand for them and makes them desirable. Crafts not in demand with the dynasty may be in demand with the other inhabitants of a city. However, that would not be the same thing, for the dynasty is the biggest market.95 There, everything can be marketed. It does not make any difference whether it is little or much. Whatever is in demand with the dynasty is of necessity a major article. On the other hand, the demand of the common people for a particular craft is not general, nor is the business that the common people can provide of large volume.
God has power to do what He wishes.