We begin the fourth chapter of Tractate Bava Metzia. In this Mishnah, the tractate turns to a new topic that will span many chapters: laws of commerce. At the foundation of the laws of commerce stands the transaction in which a person exchanges goods (we will deal with services later). Therefore, the first topic that the Mishnah addresses is: what constitutes an act of acquisition, and at what stage do the goods change hands and acquire a new owner.
This definition is extremely important. Once the exact moment of the transfer of ownership is established, we know at every stage who is the owner of the goods and who is responsible for them - in the event of loss, a lightning strike, and the like. Therefore, we must know at any given moment to whom the goods belong, and at what point the rights and responsibilities pass from one party to the other.
Acquisition by Barter:
In days gone by, a large portion of transactions were carried out not with monetary payment, but through barter. One person has wine and another has oil, and the two agree to exchange the wine for the oil. The standard act of acquisition is taking physical possession of the object: pulling it, and sometimes lifting it, when appropriate. As we saw in Tractate Kiddushin, there are various types of acts of acquisition. Once the parties have agreed on the terms, taking the object is what executes the transaction - the oil becomes mine once I lift it, and simultaneously the wine transfers to the ownership of my counterpart. Without prior mutual agreement there is no acquisition here at all, but rather taking something that is not mine.
It is worth clarifying that exchanges appear in the Torah and the Gemara in two ways:
Actual barter: An exchange of equal value, such as wine for oil, where the two items are considered to be of identical value, or where each of the parties is willing to exchange them for fair consideration.
Symbolic acquisition: An acquisition of a symbolic nature. If I wish to transfer wine or a cow that is not physically present, the buyer cannot perform an act of acquisition on them. In such a case, the buyer hands the seller a handkerchief (or any other object: a kippah, a pen, and the like), and the seller lifts it as if he is buying it, and in exchange, the rights to everything being sold pass to the buyer. Even though the handkerchief is not equal to the value of the cow being sold, the act of acquisition performed with it is sufficient to execute the transaction, and afterward, the object is usually returned to its owner, since the seller has no desire for it at all.
The rule that emerges from here is: when two objects change hands, it is sufficient that one of them is taken by one of the parties for the transaction to be completed, and the ownership rights of the second object transfer automatically.
Produce and Money - What Executes the Acquisition:
Already in the period of the Mishnah, the method of commerce had changed: one party sells goods, referred to in the language of the Sages as "produce" (and the intention is not specifically to crops, but to any merchandise, and even a cow), and the second party pays with money, "coins". Here a fundamental issue arises: it is not the payment of money that executes the acquisition, but rather the taking of the goods. For one who gives money for a cow - the cow does not become his through this; taking the cow is what makes it his, and from that moment the obligation of payment falls upon him. And since the money does not execute the acquisition, we must identify in every transaction what is the payment (the money) and what is the merchandise (the produce).
Under normal circumstances the distinction is simple, since money has two foundational characteristics: it is a store of value, used to retain value over time (like gold coins, silver coins, or banknotes), and it is a medium of exchange. The second characteristic is the essential one for our Mishnah: not everyone is interested in accepting my oil or wine in barter, but everyone is willing to accept money in exchange for what they seek to sell. Therefore, when it is clear which is the medium of exchange in the transaction - the money - it is the case that it does not execute the acquisition, whereas the second item, the goods, is what executes it.
However, sometimes the distinction becomes blurred, and the Mishnah immediately turns to this. There are transactions in which both parties involve items that in other contexts would be considered money. The simple example: someone exchanging shekels for dollars. The acquisition is finalized, and there is no longer an option to back out, the moment the goods change hands and not the moment the payment changes hands. But which of them is the goods and which is the payment?
The Rule of the Mishnah:
In a transaction where both items could be considered money, the item considered produce, meaning merchandise, is the one that is more difficult to use as a medium of exchange in the local economy. In Israel, when exchanging shekels for dollars, the shekels are the money and the dollars are the merchandise, since it is difficult to pay with dollars in stores, whereas shekels are accepted in every store. In America, in that exact same transaction, the shekels are the merchandise, since it is difficult to trade with them there, whereas dollars are easily given and are therefore the money. The item that is less easy to use as a medium of exchange is what effects the transaction, because it is the merchandise in that context, and the other is the payment for it.
The text of the Mishnah:
The Mishnah opens with transactions of coins for coins. It must be prefaced that the words "silver" and "gold" here mean silver coins and gold coins; silver and gold bullion are not money at all, but rather absolute merchandise.
"Hazahav koneh es hakesef, vehakesef eino koneh es hazahav" - In the time of the Mishnah there was a fixed exchange rate, and generally twenty-five silver coins of a certain weight were counted against one gold coin. In a transaction of silver for gold, the transaction is completed by taking the gold and not by taking the silver, since the silver is the means of payment and the gold is the merchandise. The reason: silver coins are easily accepted in every store in the city, whereas gold, being a coin of particularly high value and due to the risks involved with it, is accepted with less willingness. This is similar to someone entering a candy store with a hundred-dollar bill, which the store owner is not eager to accept, partly because he does not have change. And although it says "acquires the silver," the meaning is that taking the gold creates the monetary obligation to hand over the silver coins in exchange; whereas taking the silver coins does not effect the transaction and does not transfer ownership of the gold.
"Hanechoshes konah es hakesef, vehakesef eino koneh es hanechoshes" - Copper (and its alloys, bronze and brass) is considered merchandise relative to silver coins, since its value is low, handling it is cumbersome, and it is difficult to give to people; no one is eager to accept a handful of pennies as payment. Therefore, taking the copper coins, which are the merchandise, is what effects the transaction, whereas taking the silver coins in exchange for them does not effect it, since they are the money.
"Maos haraos konos es hayafos, vehayafos einan konos es haraos" - According to the Bartenura, this refers to coins that were taken out of circulation: a new king arose, and the coins of the old image ceased to be used. These coins are still made of silver and their silver content remains, and in another country they will still accept them, so they are considered money in a certain sense; but in the place itself no one accepts them, because the government forbade their use. For this reason they are the merchandise, whereas the new coins are the medium of exchange.
Tosafos does not accept this plain meaning and asks: what is the novelty here? Is it not obvious that if the government took a coin out of circulation, it can no longer serve as money. Therefore, Tosafos explains that this refers to coins that became worn down.
In our times, the money in our hands is "fiat money" that has no intrinsic value at all: merely a piece of paper, and its value stems from the banks and the government, and by this power one can pay taxes and debts with it. In the time of the Mishnah, however, the government stamp was intended to confirm that the silver content indeed exists in the coin, but its value stemmed from the actual silver in it. Over time the coins wear down and their silver content decreases: instead of ten grams of silver, nine and nine-tenths remain, and at a certain point no one is willing to accept them at their face value, because they do not have enough silver to justify it. Therefore, Tosafos says that in a transaction of worn coins against sound coins, even though both might be considered money in other contexts, in this context the worn ones are the merchandise and the new ones are the money.
The Mishnah continues: "Ha'asimon koneh es hamatbeia, vehamatbeia eino koneh es ha'asimon" - an asimon is a disc of silver, copper, or gold used as a coin, but the government stamp turning it into an official coin has not yet been minted on it; a smooth piece of metal. Even though in other contexts people will accept these pieces as silver coins, since they have the shape of a coin and are made of silver, in this context a person would much prefer to receive the minted coin whose value is guaranteed, over the estimated value of an unminted coin. Therefore, the asimon is the merchandise, and taking it creates the obligation to hand over the other side, the minted coin; whereas taking the minted coin does not transfer ownership of the asimon, of the smooth piece of metal.
Movables and Coin:
Here the Mishnah returns to the main point we opened with: "Hametaltelin konin es hamatbeia, vehamatbeia eino koneh es hametaltelin" - in a transaction of movables, any merchandise whatsoever, for coins, the coins are always the money, and therefore handing them over does not effect the transaction; whereas taking physical possession of the movables up for sale, by lifting or an equivalent action, is what effects the transaction.
And the Mishnah concludes: "Zeh haklal: kol hametaltelin konin zeh es zeh" - usually, "zeh haklal" comes to summarize what was stated above, and sometimes even to add to it, but always based on the previous principles. Here this is not the case, but rather a completely new point was stated, and therefore many, including the Rif and the Rosh, have the textual variant to delete the words "zeh haklal." The content of the halachah: in a transaction of barter, where merchandise is exchanged for merchandise - the cow for the horse, the wheat for the barley, the oil for the wine - each one of them acquires the other. Once one of the parties takes the object of the other, the other side of the transaction automatically transfers to the ownership of his friend, since it is a transaction of barter. It turns out that each one of the parties can effect the transaction by taking the object he is to receive and performing an appropriate act of acquisition on it.
Everything stated in the Mishnah is practical halachah. Nevertheless, two unknowns remain here that were not discussed in it:
We said that silver is considered a coin relative to copper coins and gold coins. What is the law when copper and gold are exchanged for each other? It is possible that the matter depends on the custom and routine of the local market.
What is the law in a transaction of silver for silver, such as one who gives two half-shekel coins for a one-shekel coin? In such a case both sides function as actual money, and there is no merchandise here relative to each other. Therefore, the transaction will not be finished until each of the parties takes his money, since there is no specific merchandise passing from hand to hand here, but rather money for money.
In summary: In this chapter we transitioned to the laws of commerce, and we learned that the act of acquisition is accomplished by taking the merchandise and not by transferring the payment. We examined the two modes of exchange, the distinction between "produce" and "coins", and the rule that when both sides of the transaction can be considered money, the item that is harder to trade with in the local economy acts as the merchandise that effects the acquisition. From this, we explained the laws regarding gold and silver, copper and silver, bad coins and good coins, unminted metal and minted coins, and movable items acquiring one another.