Argument 398: on Exchange in a Strict Sense and Its Types. Is the Exchange Dealer's Activity Licit?(Treatise on Money) (Excerpt‪)‬

To exchange, in a strict sense, and we already pointed out in Argument 396, is no less than to trade money for money, and it is not necessary for the money that is exchanged to be different from the one that is received as far as the material, shape, or engraved seal on the coins, and in spite of Juan de Medina's opinion. (1) Because, as Soto (2) believes, if the money were handed over in one place to be paid or handed back somewhere else it shall be a real exchange, even if the money to be paid back is no different from the one received as far as the material or the seal. Even if the parties who carry out the barter in the sense described in Argument 397 have the same name, (3) and both may be equally called barterer and barteree, (4) they are not called the same in the exchange, nor do they carry out the same occupation. Because the person who is asked for the exchange may rent out the services and ability requested of him, and for this he may justly charge something more than the amount he exchanges, as shall be evident for what we shall proceed to explain. For this reason, in order to make a distinction between both parties involved in the exchange, they are given different names: the person to whom the exchange is requested, and who lends his services and resourcefulness by someone else's request is called an exchange dealer, especially if he holds the office in a public condition. He is also called numulario, trapezita, collybista, and argentarius, although some of these names may sometimes have a broader meaning. See Covarrubias (5) for further discussion on this issue. In Spanish he is called vanquero (6) [sic]. Conrado (7) calls the person who solicits the exchange campsarius; Medina and others give him the same name, because just as the borrower is the one who receives a loan, the donee, the recipient of a donation, and the legatee one to whom a legacy is bequeathed, he who receives money in exchange is called a campsario.