Who said "The mind that refuses to grow is already dead."?

This quote is attributed to Diocletian.

The mind that refuses to grow is already dead. - Diocletian

"The mind that refuses to grow is already dead."

Diocletian

Emperor Ancient Rome 245–316

"A leader who does not consult is a tyrant in waiting."

"The greatest power lies not in conquest, but in knowing when to lay down the sword."

"To govern well, one must first govern oneself."

"Patience is the virtue of those who understand the weight of empire."