20. In contrast with the preceding, however, that is to say, under a burdensome title, soldiers acquire their military pay, or what is assigned them in place of that pay; also all those things which come to us by burdensome pacts or contracts, for example, things acquired by payment of money, by exchange with a thing of equal value, by labour or effort, even though some element of profit be not altogether lacking here. Thus, it is by truly burdensome title that merchants acquire property, even though they sell their merchandise for more than they paid for it; since the labours and dangers of transporting and handling the merchandise are regarded as being equivalent to the gain. For this reason even usury upon money let out at interest belongs here, for the obvious reason that, while this money is lent for another’s use, besides the risk involved of losing the loan, it cannot be paid out for other profitable uses by its owner. Nay, even money or property which is acquired on wagers, by so-called urns of fortune, or by any kind of game, belongs here; for there was a contract also in the case of all those things, and my money was exposed to equal risk with that of another; although contracts of that kind have in some places been altogether prohibited by civil laws, or else the resources of legal action have been denied against those who are unwilling to abide by them. No less accompanied with burden is the income of princes which the privy purse receives out of the revenues of the state for the expenses of single individuals or their own household; for this is granted as some measure of compensation for the undertaking of cares and labours in behalf of the state. And as for the rest of the revenues, those, namely, which are spent upon public uses, nothing but the administration and distribution of these has been left to princes, and therefore, when these revenues are brought into the treasury, they cannot properly be said to be acquired for the princes.
Into this class falls also that which is seized from the enemy in a just war.35 For although he who gives me a just cause for making war would also, as far as in him lay, be giving me the right of taking all that is his own, however far, perhaps, this would exceed the injury that has been done by him (as will be shown somewhere), and therefore, <41> assuming that I have a just cause for making war, nothing further is required for my laying hold of his possessions than the act of occupation; nevertheless, because, aside from the fact that these are imputed to the payment for damage which has been received, such occupation cannot take place without expenses, perils, and labours, not to mention the uncertain cast of the dice of Mars, property of this kind is regarded as passing from one owner to another under burden. In war, moreover, the property of the enemy becomes ours, his movable property, indeed, when it has been brought behind our outposts; but his immovable property, even though for a time it may be held under our power [potestate], becomes ours only when it has so been occupied by us that for the time being the enemy has left open to him no avenue of approach to it. Nevertheless, a quieted possession of the same is obtained only at the time when the enemy has either been utterly annihilated or scattered, or else has also by a pact given up his claim to such property. Here, furthermore, it must be noted that, if among the things taken from the enemy there be some which have been taken from some third party likewise, in case this third party has given up the effort to recover them, and has left them to the quieted possession of the second, then he cannot demand back that property from the last holder. For to property which has been taken away in a just war I am understood to have lost at the same time every right. The same thing happens when I suffer my right to a thing which has been taken away from me in any way at all, to expire by neglecting to recover it, or at least to protest against the wrong, or by entering into transactions with the one who took it away.36 Also the obligation of restoring a thing which has been taken away unjustly does not pass from the one who took it away to the latest holder, and that because this obligation inheres in the person of the former, and does by no means attend the thing which the first possessor has already regarded as derelict. But if, in truth, the first possessor has preserved his right, then he will be able rightly to recover his property from the last holder, with this proviso, however, that he is bound to make good to the latter the effort expended in recovering it.
21. These are about all the ways in which, either as a whole or as individual items, things are acquired, as they exist at different times in the world. Furthermore, that method of acquisition is in the highest degree natural, by which the natural and artificial increments and fruits of our property or our industry and any or all improvements of the same, come to us. Now this means is extremely widespread, and it is the most frequent as well as the most fruitful of them all, especially inasmuch as most things either take on natural increments and produce fruits of the same kind, or are capable of being made better, larger, and more fruitful by human industry. Now increments and fruits of things are either merely natural, or merely artificial, or mixed. To <42> the first class can be referred trees and other plants which, without man’s cultivation, grow out of the earth, and the fruits of the same which do not need the labour and industry of man for their production. To this class also you can assign alluvium, in so far as it is deposited without human effort, the violence of the stream adding to one man’s farm a bit of soil which has been cut away from somewhere else, and the process being one of silent increments. It is recognized that this alluvial deposit comes to belong to the owner of the farm, principally for the reason that no one can positively prove that it was to this particular spot and nowhere else that parts taken from his farm had been added; and likewise that whatever has been placed there is from his land alone and from nowhere else.
To the third class belong those increments and fruits in which the operation of nature as well as the industry and effort of men concur. Such are all manner of crops which are improved through cultivation by man, trees which put off their sylvan nature as a result of ingrafting, and the fruits of the same; likewise the offspring and fruits of animals which are fed by men, or of those animals whose offspring and fruits are not produced at all without human effort, or else have to be sustained thereby. The fruits of animals I call milk, wool, hair, feathers, teeth, deciduous horns, and the like.
To the second class we assign those things which, due to human skill, put on a form that is fit for definite uses, such as are practically all things with which the industry of workmen and artisans is occupied. Their industry is accustomed to fashion these rude benefactions of nature, as it were, for the most convenient uses of human life.
22. Here also may suitably be placed that which otherwise is a common matter of dispute among the jurisconsults, whether, namely, in regard to the production of a species out of material belonging to another, the artificial form follows the material, or the material follows the form.37 Although the civil law, by virtue of sovereign authority, might have settled this controversy by distinguishing between the species which can be reduced to their earlier form and those which cannot, so that in the first class the form yields precedence to the material, in the second class the opposite is the case; nevertheless, for those who follow only the law of nature, the discrimination must be made as to whether a certain person applied his industry to the elaboration of material belonging to another either through error, or from a credibly presumed willingness on the part of the owner of the material; or rather did so with guile, and with the intention of defrauding him of the material by this means; and, in the next place, whether the material, or the value of the art employed, was the greater. For he who knowingly, and with malice aforethought, has given my material a new form so as to defraud me of it by this means, has neither acquired any right to <43> the material, nor is he any more able to demand from me the reward of his labour, than is the housebreaker, because with a great deal of trouble he has made a new entrance into my house. But if he has acted through error due not to absolutely heedless negligence, that is, if otherwise that material might easily have been replaced from elsewhere, or was not so very necessary to the owner, or under other circumstances he would have had it for sale, the option still remains with the owner as to whether he shall accept pay for the material and leave the product to the artisan, or prefers to pay for the effort and keep