EMPTIO. In the Roman and civil law. The act of buying; a purchase. — Emptio bonorum. A species of forced as- ... if the price is fixed and not subject to fluctuation, but is to be paid whether the gain be greater or less, it is called emptio spei.

What is Emptio REI Speratae?

A purchase in the hope of an uncertain future profit; the purchase of a thing not yet inexistence or not yet in the possession of the seller, as, the cast of a net or a crop to begrown, and the price of which is to depend on the actual gain.

What are thing having a potential existence?

Article 1461 provides that “Things having potential existence may be the object of the contract of sale. ... The latter concerns the sale of hope or expectancy where there is no certainty as to the thing or its quality and quantity, it is the sale of the hope that the thing shall exist.