That "thing" that he refers to is people. It is people that build a country not land, not resources, not armies. Yes, a modicum-minimum of these is required to sustain some level of initial domestic activity. But in this age of globalization, the resources that one initially possess are relegated to a mere 'contingency' status. Japan, with a population of 128 million and a landmass 1/9th-10th that of India, has a similar average population density. Many of its islands are even uninhabitable because of their volcanic mountains and tectonic activity. Even in China, where close to 60% of the landmass is occupied by the Tibetan plateau and Xinjiang, vast tracts of land are hostile to inhabitation because of cold and desert. Both countries are perfect examples of how relative resource paucity have not been allowed to hold them back. Yet, Japan never had and could never have as much potential as China. Simply because, once China started industrializing and maintained itself along that growth trajectory, the eventual resolution of 'technological-coefficients' <fancy jargon for levels of technology in industrial production> would ensure, that the population-compounded consumption, investment and gross production values it could achieve would far exceed anything Japan could attain in the long-run. The same applies in the context of India-Brazil. Resources, in terms of their extractive-industrial use, have assumed less significance in this day and age. India, however, faces a unique scenario, in that it is industrializing at a time when another voracious, large power with an even larger appetite for resources, is industrializing and has been industrializing for some time now; and the relative paucity of resources and the associated demand-time lag, and consequently higher prices, may impinge on its growth.
The other thing that is important for nation building is good relations, and this is particularly true in the case of more diminutive countries. We have already seen how Pakistan's fortunes have changed, once it got on the 'wrong side of the fence.
Resources, however are still important for one singular reason; and that is because they afford a degree of strategic-leverage over neighboring states. And this is particularly true for a country like India, where in an age of ever growing water-scarcity, and exceedingly tight water-pressures, the failure to come to a consolidated agreement will militate necessary action.