  With the emergence of post-colonial nations following the Second World War, long run economic development became prominent in economic studies. By the early 1960s it had become clear that Ramsey’s paper is the natural starting point for studying the welfare economics of the long run, not only for pursuing optimum development in centrally planned economies (Chakravarty, 1969), but also for use in social cost-benefit analysis of public investment in mixed economies (Arrow and Kurz, 1970), the choice of technology in labour-surplus economies (Little and Mirrlees, 1968, 1974), and more recently, the welfare economics of climate change (Cline, 1992; Nordhaus, 1994; Stern, 2007). The number of trails Ramsey laid was remarkable. In academic economics it is one of the dozen or so most influential papers of the 20th century.