Lee de Forest's 1906 talk on his vaccum-tube experiments

de Forest was earned a physics PhD from Yale in 1899. His experiments with a lot of ideas that were new at the time led to broadcast radio, microphone recording, talkies, amplified music, and broadcast TV. It's argueable that his cultural influence outweighed Edison's. Then, just like Tesla for a long time (and other radio and TV pioneers) he was disappeared.

This 1906 talk to the New York AIEE conference reveals what was going through his head when he discovered weak-signal amplification.

Edit: Corrected the PhD year from 1896.