You're dealing with a reservoir that extends over hundreds, perhaps thousands, of square miles. It's just a matter of figuring out the technology to extract that.

Society needs hundreds of hundreds of thousands of Chen Guangbiaos.

Rust spores can be carried by wind currents hundreds or even thousands of miles, even across oceans. They are eventually brought down to earth by rain, and a leaf that's been wet for several hours is needed in order for a spore to germinate and infect a plant.

Admitting hundreds of thousands of infiltrators is an existential threat to the State of Israel.

We're probably 2.8 square miles, with 28 miles of coastline.

We have 45,000 square miles of geography in Ohio.