Who said "The gem cannot be polished without friction."?

This quote is attributed to Christopher Peterson.

The gem cannot be polished without friction. - Christopher Peterson

"The gem cannot be polished without friction."

Christopher Peterson Change

Psychologist American 1950–2012

"Other people matter."

"The good life is not a static state. It is a direction."

"What you do with your life is up to you. Fish for trout, accept it."

"Positive psychology takes seriously the fact that people want more than just to not be miserable."

"Change brings new opportunities."

"Every day is a new opportunity."

"Healing doesn't mean forgetting."

"You either get better or you get bitter."