  The linear technology (eq. 11a) and the iso-elastic \(U\)-function (eq. 11b), when taken together, have offered deep insights even though we have restricted the discussion to pen-and-paper calculations here. The functional forms are not believable; nevertheless, Ramsey made use of them. His paper showed that unbelievably simplified models, provided their construction is backed by strong intuition, can illuminate questions that are seemingly impossible to frame, let alone to answer quantitatively. That has been Ramsey’s enduring gift to theoretical economics.