I learn more from 10 minutes of a podcast than from an hour with most books.

So why would two people talking teach me more than a book someone spent years writing?

Dale Carnegie tested his advice on a classroom before he wrote it down. He taught public speaking at night to people in business. His students needed more than speaking lessons, so he searched for a textbook on getting along with people.

He came up empty and wrote a short talk instead.

Each season he gave the talk and sent the class out to test it. A week later they reported back.

The rules started on a card the size of a postcard, then grew into a leaflet and a series of booklets. Years later, the booklets became How to Win Friends and Influence People.

The book has sold more than 30 million copies.

Yuval Noah Harari's Sapiens also began as lectures to his history students.

The comedian Jerry Seinfeld tests each joke on a crowd before he keeps it. After his sitcom ended, he retired his old jokes in an HBO special. Then he built a new act from nothing.

He'd show up unannounced at basement comedy clubs and try new jokes one at a time. The documentary Comedian filmed it.

It took him more than a year to build a full hour.

Alone with a page, you can spend an hour trying to sound smart. Across from a listener, you aim to be understood.

What could you explain to a friend before writing it?