  How should we conceptualise human well-being over time and across generations? How ought the interests of people in the distant future to be taken into account when we make our own decisions? How much of its output should a nation invest for the future? In which assets should that investment be made? What should be the balance among private, public, and communitarian investments in the overall investment that a generation makes for the future? How much should the world spend in countering global climate change?