Montesquieu

Aristippus, fol­lo­wing his ship­wreck, was able to swim to a nearby shore ; he found geo­me­tri­cal figu­res tra­ced in the sand, and was over­come with joy, jud­ging that he had come upon a Greek peo­ple and not bar­ba­rians.

Assume you are alone, and arrive by some acci­dent among an unk­nown peo­ple : if you see a coin, you may be sure you have come upon a civi­li­zed nation.

Cultivation of the land requi­res the use of money. This culture depends on many arts and much know­ledge, and we always find the arts, know­ledge, and needs pro­gres­sing toge­ther. All toge­ther they lead to the esta­blish­ment of a sign of values.

Mountain streams and forest fires1 have revea­led to us that metals are in the ground. Once they have been sepa­ra­ted from it, it has been a sim­ple mat­ter to put them to use.

That is how Diodorus tells us that shepherds found gold in the Pyrenees.