2. The price should consist in a sum of money. It has been much doubted whether it can consist in anything else, as in a slave, a piece of land, or a toga. Sabinus and Cassius thought that it could. And it is thus that it is commonly said that exchange is a sale, and that this form of sale is the most ancient. The testimony of Homer was quoted, who says that part of the army of the Greeks procured wine by an exchange of certain things. The passage is this:-
The long-haired Achaeans procured wine,
some by giving copper, others by giving shining steel,
others by giving hides, others by giving oxen, others by giving slaves.
The authors of the opposite school were of a contrary opinion: they thought that exchange was one thing and sale another, otherwise, in an exchange, it would be impossible to say which was the thing sold, and which the thing given as the price; for it was contrary to reason to consider each thing as at once sold, and given as the price.
Maintained that exchange
The opinion of Proculus, who maintained that exchange is a particular kind of contract distinct from sale, has deservedly prevailed, as it is supported by other lines from Homer, and by still more weighty reasons adopted by preceding emperors: it has been fully treated in our Digests.
3. As soon as the sale is contracted, that is, in the case of a sale made without writing, when the parties have agreed on the price, all risk attaching to the thing sold falls upon the purchaser, although the thing has not yet been delivered to him.
Therefore, if the slave dies or receives an injury in any part of the body, or a whole or a portion of the house is burnt, or a whole or a portion of the land is carried by the force of a flood, or is diminished or deteriorated by an inundation, or by a tempest making havoc with the trees, the loss falls on the purchaser, and although he does not receive the thing, he is obliged to pay the price, for the seller does not suffer for anything which happens without any design or fault of his.
On the other hand, if after the sale the land is increased by alluvion, it is the purchaser who receives the advantage, for he who bears the risk of harm ought to receive the benefit of all that is advantageous. If a slave who has been sold runs away or is stolen, without any fraud or fault on the part of the seller, we must inquire whether the seller undertook to keep him safely until he was delivered over; if he undertook this, what happens is at his risk; if he did not undertake it, he is not responsible.
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