In the Startups = Growth essay, Graham states:
For a company to grow really big, it must (a) make something lots of people want, and (b) reach and serve all those people. Barbershops are doing fine in the (a) department. Almost everyone needs their hair cut. The problem for a barbershop, as for any retail establishment, is (b). A barbershop serves customers in person, and few will travel far for a haircut. And even if they did the barbershop couldn’t accomodate them. 
Writing software is a great way to solve (b), but you can still end up constrained in (a). If you write software to teach Tibetan to Hungarian speakers, you’ll be able to reach most of the people who want it, but there won’t be many of them. If you make software to teach English to Chinese speakers, however, you’re in startup territory.
Most businesses are tightly constrained in (a) or (b). The distinctive feature of successful startups is that they’re not.
Then, all the way at the bottom of the essay, he adds the footnote , which for me was a very important point:
Strictly speaking it’s not lots of customers you need but a big market, meaning a high product of number of customers times how much they’ll pay. But it’s dangerous to have too few customers even if they pay a lot, or the power that individual customers have over you could turn you into a de facto consulting firm. So whatever market you’re in, you’ll usually do best to err on the side of making the broadest type of product for it.
Whenever I fly along the East Coast – which I did a fair bit of the past three years for business between Richmond, VA and Newark, NJ – I like to look out the window of the airplane at all the towns and houses below me. So many houses. At night, so many streetlights and porch lights.
Then I start thinking, what could I make to sell to all these people?
This is the kind of thinking that Graham is talking about. Next time you’re on an airplane – or don’t wait, “fly over” a bunch of towns in Google Maps – and ask yourself the same question. That kind of literal “high-level” perspective can be helpful to get the creative gears going.