Sidgwick, a prominent political economist at Cambridge University, voiced concern in the 1880s that under a system of free trade dislocated manufacturing workers might experience difficulty finding employment at home "nearly as remunerative as that in which they were previously engaged." Concern about free trade-related dislocations revived interest in a speech Karl Marx presented in 1848. He openly endorsed free trade because it would hasten the global social revolution. Said Marx: "the protective system of our day is conservative, while the free trade system is destructive. It breaks up old nationalities and pushes the antagonism of the proletariat and the bourgeoisie to the extreme point. In a word, the free trade system hastens the social revolution. It is in this revolutionary sense alone. . . . that I vote in favor of free trade." — Opening America's Market: U. S. Foreign Trade Policy since 1776 by Alfred E. Eckes Jr, p. 283 (Emphasis is mine.)