[PAULUS libro secundo institutionum. ] §44.7.3.prObligationum substantia non in eo consistit, ut aliquod corpus nostrum aut seruitutem nostram faciat, sed ut alium nobis obstringat ad dandum aliquid uel faciendum uel praestandum.
[PAULUS, from the second book of the Institutes.] The substance of obligations consists not in making some property ours or some servitude ours, but in binding another person to us to give, to do, or to perform something.
§44.7.3.1Non satis autem est dantis esse nummos et fieri accipientis, ut obligatio nascatur, sed etiam hoc animo dari et accipi, ut obligatio constituatur.
Moreover, it is not sufficient for the creation of an obligation that the money belongs to the giver and becomes the property of the receiver, but it must also be given and received with this intention, that an obligation is established.
itaque si quis pecuniam suam donandi causa dederit mihi, quamquam et donantis fuerit et mea fiat, tamen non obligabor ei, quia non hoc inter nos actum est.
Therefore, if anyone should give me his money for the purpose of a gift, although it belonged to the giver and becomes mine, yet I shall not be obligated to him, because this was not what was transacted between us.
§44.7.3.2Uerborum quoque obligatio constat, si inter contrahentes id agatur: nec enim si per iocum puta uel demonstrandi intellectus causa ego tibi dixero 'spondes?' et tu responderis 'spondeo', nascetur obligatio.
An obligation by words also is established only if this is what is intended between the contracting parties; for if, say for the sake of a joke or for the purpose of demonstrating understanding, I say to you "Do you promise?" and you answer "I promise", no obligation will arise.