I sometimes explain it like this:<p>"Consider the following idea; there is a billion dollars[1] worth of Gold sitting in one mountain in the Sierra Nevada range just south of Lake Tahoe."<p>This isn't theory, you can read the US Geological survey reports, you can do your own assay. There is a billion dollars sitting there for the taking.<p>That the gold is there is the "idea", that you have to process an entire mountain (roughly 50 cubic miles of granite) to extract that gold is "execution."<p>Now here is the punchline. There is no place left in that mountain where you can just dig a hole and pull out a profitable amount of gold. That is because all the ideas for getting the gold out 'easily' have already been tried.<p>There are not a lot of genuinely new ideas, but there are new versions of an idea when things change in a fundamental way. If someone created something like a Tunnel Boring Machine which could suck in granite, pull out gold, and return the results (with equivalent structural integrity :-)) as it passed through. <i>That</i> would make getting the gold out of the mountain more feasible.<p>[1] This used to be a 100 million dollars worth of gold when it was $100/oz, now at > $1000 it is more than a billion dollars. And like oil, which cost more than $50 a barrel to remove was 'worthless' in the 70's is now profitable in the > $100 a barrel days of oil.