Sources of raw materials include mines, cleared land, oil wells, lumber, fisheries, and things of that nature are what economists call intermediary goods. Intermediary goods are the parts, the materials the ingredients that are passed from stage to stage through the productive process, and are used to produce the things that come out at the other end of the factory. Economic growth means that the total quantity of these things increases, and when the total quantity of these things increases more can be produced. .
Now there are two essentially different ways, which they can potentially increase. We can produce more of the same thing or we can have more of the same machines, tools, and factories of the same kind producing the same output, more raw materials of the same kind etcetera. More of the same would mean economic growth signifying that the total productive capacity of the economy had increased. But historically, and this is a crucial point "historically there has been no economic growth with out better machines and tools, better factories, better products, better goods, better sources of raw materials."" (Buechner Recording) I am going to take that as a basic fact. Economic growth fundamentally, and essentially takes the form of better goods and services of all kinds. I'm now going to assume that the "marginal product of capital does not decrease-(Hazlitt 40) the assumption that it does I think is clearly contrary to fact. That makes a huge difference in the theory of economic growth. Where do we start with better? We start with better know how in the means of new ideas, technological discoveries, and inventions. These ideas have to be put into a concrete material form of better machinery, plants, structures, and tools that can be classified under the general heading technological progress. According to Hazlitt if you get that, and you get total productive capacity increasing faster than the population grows you get a rising standard of living.