Did William James ever say, write, or think anything about human beings using only 10% of our brains? No, nope, and no. An investigation:
* * * *
Blame Lowell Thomas. He’s as good a person to blame as anyone.
Because if you are going to make a claim—about anything at all—in the forward of a book that goes on to sell tens of millions of copies and remain continuously in print for nearly 80 years, you are going to be responsible for authoring a claim that will stick in the communal mind, that will become a part of how we as a culture think we understand ourselves. And as Lowell Thomas might have put it himself in his folksy manner of speaking, it was a doozy.