Who said "The mind that does not challenge itself cannot grow."?

This quote is attributed to Hermann Ebbinghaus.

The mind that does not challenge itself cannot grow. - Hermann Ebbinghaus

"The mind that does not challenge itself cannot grow."

Hermann Ebbinghaus Courage

Psychologist German 1850–1909

"Memory is the mother of all wisdom."

"The true art of memory is attention."

"We live in succession, in division, in parts, in particles. Meantime within man is the soul of the whole."

"Without repetition, nothing is learned."

"Never let fear stop you from chasing your dreams."

"Courage is being afraid but doing it anyway."

"Sometimes you gotta do what you gotta do."

"Sometimes you have to be the monster to stop the monsters."