 \(\delta \gt 0\) implies \(e^{-\delta} \lt 1\). That means \(e^{-\delta(\tau -t)}\) tends to zero exponentially as \(\tau\) tends to infinity. In the latter part of his paper Ramsey (1928: 553–555) did use equation (4) to study the problem of optimum saving, but he did not approve of the formulation. Instead, he wrote (p. 543) that to discount later \(U\)’s in comparison with earlier ones is “… ethically indefensible and arises merely from the weakness of the imagination.” In a book that inaugurated the formal study of economic development, Harrod (1948: 40) followed suit by calling the practice a “… polite expression for rapacity and the conquest of reason by passion.”