from tiny acorns

A good art collector has a feel for what's going to be big. He or she probably sees an outrageously large amount of art in a short period of time, and is somehow able to separate the wheat from the chaff - to identify what's going to be worth a continued look and what isn't. It doesn't really matter whether what's worth that continued look is worth it for truly artistic, or simply for economic, reasons. What's important is having an eye for what's going to develop.

The small mold spores on a piece of bread have potential. They may grow into something big. And the boys who leave those sandwiches in their bags may also, with a bit more practice, become full-scale artists.