Who said "A ruler's compassion is his most formidable weapon."?

This quote is attributed to Hadrian.

A ruler's compassion is his most formidable weapon. - Hadrian

"A ruler's compassion is his most formidable weapon."

Hadrian Leadership

Emperor Ancient Rome 76–138

"Nothing is harder to bear than a good example."

"I have always strived to be the best, but I have also learned that the best is not always perfection."

"A man who fears nothing is more dangerous than a man who fears something."

"The greatest luxury is knowledge."

"A leader must be fair and just."

"Integrity is everything."

"One must take responsibility for one's environment."

"In this house, I make the decisions"