Who said "One must be civil and courteous, or one becomes a savage."?

This quote is attributed to Voltaire.

One must be civil and courteous, or one becomes a savage. - Voltaire

"One must be civil and courteous, or one becomes a savage."

Voltaire

Writer Philosopher French 1694–1778

"It is dangerous to be right when the government is wrong."

"Life is thickly sown with thorns, and I know no other remedy than to pass quickly through them."

"The perfect is the enemy of the good."

"Judge a man by his questions rather than by his answers."