Sir Arthur Lewis’ quote amply summarises the rationale for economic growth in human society. Economic growth is desired because it increases opportunities and thereby provides greater scope for action. Clearly, there is an intertemporal dimension to this. Enhanced scope for action today may be available only by reducing such scope in the future. The environment is the principal example of this. But it is, by no means, the only one. For example, the no-Ponzi game condition restricting the growth of public debt (see Blanchard and Fischer 1989, for example) such that the state (or private individuals) do not borrow indefinitely from future generations in order to finance current consumption, is surely part of the same concern as, for example, that of preserving biodiversity. The stock of natural, human and physical capital must all be maintained at some, as yet vaguely defined, ‘optimal’ levels over time. The message that we live off resources borrowed from future generations rather than those inherited from our ancestors has to be enshrined as a basic principle of economic constitutions the world over.