In one sentence, Hemingway quickly gives us a lesson on how to write and what to write about. And not only does Hemingway inform us on the art of writing he lets us know how writing can be an effective tool to work out issues.
Time and time again, I've used writing (not that I think I'm any good or that I'm anything like Hemingway up there) to write about things that have hurt. It's these times that I cherish the most, the times where I can take a somewhat traumatic experience and turn it into something that I'm proud of or use writing as something to get rid of the inner turmoil I find myself in.
It's important for me to remember what Hemingway said every time I put pen to paper or finger to keyboard. Write clear. Write honest. Write true.