Who said "To doubt is to think; to think is to progress."?

This quote is attributed to Isaac Newton.

To doubt is to think; to think is to progress. - Isaac Newton

"To doubt is to think; to think is to progress."

Isaac Newton Courage

Mathematician and Physicist English 1643–1727

"If I have seen further, it is by standing on the shoulders of giants."

"The greatest force in the universe is not gravity, but human potential."

"I can calculate the motion of heavenly bodies, but not the madness of people."

"Nature and nature's laws lay hid in night; God said, Let Newton be! and all was light."

"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."