Institutionum libri
Ex libro III
Dig. 44,7,2Idem libro tertio institutionum. Consensu fiunt obligationes in emptionibus venditionibus, locationibus conductionibus, societatibus, mandatis. 1Ideo autem istis modis consensu dicimus obligationem contrahi, quia neque verborum neque scripturae ulla proprietas desideratur, sed sufficit eos, qui negotia gerunt, consentire. 2Unde inter absentes quoque talia negotia contrahuntur, veluti per epistulam vel per nuntium. 3Item in his contractibus alter alteri obligatur de eo, quod alterum alteri ex bono et aequo praestare oportet.
The Same, Institutes, Book III. Obligations are contracted by consent in the case of purchases, sales, hirings, leases, partnerships, and mandates. 1We say that obligations are contracted by consent in these ways, because formality of words or writing is not essential; but it is sufficient for those who transact the business to consent. 2Hence such obligations may be contracted between parties who are absent, as, for instance, by letter or by messenger. 3Moreover, in contracts of this description each of the parties is bound to the others for whatever should be done, consistent with justice and good faith.