(M445) That in the case of some slaves their value to their master consisted in their _mandattu_ is clear from the fact when a master sold a slave and did not at once hand him over, the seller had to pay a proportional amount of this fee to the buyer.(452) Of course, in transferring a slave to another owner, the seller could not separate him from his property. That was his own. A slave who had acquired a fair amount of wealth, or was earning well in trade, would produce a higher income to his master and sell for more. What was sold then, was an interest, the master’s, in his slave’s work. Hence prices varied very much. We are not always able to see what was the reason of the high price, but it was evident then to those who made the bargain. An average price in the later Babylonian era seems to have been twenty shekels, the interest on which at the usual twenty per cent. would be four shekels. This, then, was the annual value of a slave above his keep. If the keep amounted to about eight shekels _per annum_, that gives the value of a slave’s work as twelve shekels yearly. This is what an unskilled slave was worth to his master. If, then, a man married a slave-girl, he ought to pay her master about twelve shekels a year for his loss of her services. Of course, the master retained his right over her, but it seems to have been a tacit understanding that he could not sell her away from her husband. So really what he sold was, after all, only a right to income from her husband of twelve shekels a year. The children were also his born slaves, if the father was his slave. We do not know how matters would be arranged if the man was slave to one master, the wife to another. Probably this was provided against by the master giving his slave a wife from his own maids, or buying a slave-girl as wife for him.