I don't credit the creators of fire, and indoor heating, every time I turn the thermostat up. I similarly see no reason to try to credit the "original" speaker

I don't credit the creators of fire, and indoor heating, every time I turn the thermostat up. I similarly see no reason to try to credit the "original" speaker or author unless I'm using a sizable chunk of their work verbatim. Especially as while Feynman said that I highly doubt he was the first to think it. He was, very likely, merely distilling things he'd heard before much as the current author was.