How do we sort contracts in a sensible way? Not by outward features. But by what lies in contract itself. Three differences matter. Does only one person give, or do both? Is it about ownership or only about use? Is it about a specific thing or about its value?

This gives the following order.

A. Gift:

First, the gift of a thing. The aunt gives her niece a book.

Second, lending without anything in return. I lend my neighbor my ladder. He may use it. It still belongs to me. You can also lend money this way, without interest.

Third, help without pay. I look after the cat while my friends are on vacation.

A will does not belong here. For whoever dies is no longer an owner anyway. Inheritance already requires laws and a civil order.

B. Exchange:

First, exchange itself. Either thing for thing, such as potatoes for eggs. Or thing for money, that is, buying and selling. Here, money is pure value.

Second, letting. I hand over the use of something for a time and get money for it. That can be an apartment. Or it is money itself. Then it is a loan with interest.

Third, the wage contract. I work for a limited time and get a wage for it. After all, I may not sell my whole life.

A special case is services that rest on trust or great skill. For example, with a doctor or a lawyer. You cannot measure their work exactly in money. So we call the payment here an honorarium, not a wage.

C. Securing:

Sometimes a thing already belongs to me, but I do not have it yet. Then I at least want its value to be safe. A pledge serves this purpose. Whoever leaves a watch at a pawnshop gets money. The watch secures the value. Mortgage and suretyship belong here too. In suretyship, a person stands behind the debt with his word.

The pledge is not a contract of its own. It completes a contract.

Summary: There are three groups of contracts: gift, exchange and securing. The order follows from the nature of contract, not from outward features.

[zu A. Schenkungsvertrag] 1. A thing in general – 2. Use of a thing – Remain owner of the thing as a whole – Give away the wear α) of an individual thing as such – a part perishes, β) Let someone live in the house for free, work the field for free – the use – 3. Service – I remain owner of the value, of the universal. Externalization of myself – is not the case with the other kinds of gift.

[zu B. Tauschvertrag] 1. Surrender of the whole, – in exchange – Remain possessor of the value α) value as contingent.
2. Remain owner of the whole αα) as a specific and indeed individual thing, but do not remain possessor –
ββ) Use also has value – this is the universal feature of the contract of exchange – I sell the use –
ββ) only as of value – determined in itself as specific: usury, interest on money, because otherwise it is not usable as such, not as capital – nowadays different –
e.g. also grain: only owner of the value, – and also of the specific quality, yet not of it according to its empirical singularity – yet again particular grain, barley, – kind.
3. Remain owner of the absolute value.
Thib[aut, l. c.] p. 192. res fungibilis, a thing where as a rule it is a matter of indifference whether one has precisely this species (which seems rather to be the individual) or another of the same genus; res non fungibilis, where this does not hold. The former are, in case of doubt, all things that in trade and commerce are customarily alienated by number, measure, and weight. – that is, not important for the general determination –

[zu C.] Owner and possessor of the value.
[“In contracts where I alienate the use of a thing”] only the use – [I am] not in possession, but owner of the same, of the thing
This is the rational division of contracts – treated accordingly – Further circumstances, e.g. between contract and performance, who bears the loss – regret – effects of default – and an infinite multitude – brought about by the particular qualitative nature of the objects – or of conditions attached to a contract – (physical – dependent on the will – whether suspensive, resolutive –) inserted in their places
Likewise to be distinguished: pure contracts – and mixed ones, that is, with a higher ethical value – contract also in marriage, but only also – the civil side of property –
Mortgage – is formally a pledge
Suretyship – is credit, in lending generally – but not my credit. In suretyship the lender does not remain in possession of the property