But, as Solow noted, investment has its limits, owing to diminishing marginal returns. Often, these limits are not binding, but, once capital deepening is exhausted, technological progress, which makes inputs more productive in creating final value, is the long-run driver of growth.
但是，正如索洛所指出的，投资有一个极限，这是边际回报递减规律决定的。通常，投资极限并不是一成不变的，但如果资本深化潜力挖尽，那么技术进步——提高投入品在创造最终价值中的生产率——便成为长期增长动力。