For many decades now, economists have known that long-term, sustainable economic growth cannot simply be explained by increases in physical capital, natural resources or population. The accumulation of physical capital – investments in machines, buildings, roads – will increase economic output in the short run, but the mere addition of physical capital does not guarantee long-term economic growth, given the emergence of so-called marginal diminishing returns in the process of such capital accumulation. This is even more true in the case of natural resources and population growth or increased employment participation. Ultimately, long-term sustainable growth will depend on knowledge accumulation, either embodied, in smarter capital, a more efficient use of natural resources and a better-educated labour force, or disembodied, for example, as codified in patents, copyrights or trademarks. Knowledge accumulation depends on investment in education, including tertiary education, training and lifelong learning, accumulated scientific knowledge and technological advancement, and on social and institutional development. The general consensus in the literature today is that the driving force behind long-term economic growth is science, technology and innovation in its different forms and facets.