Who said "A man is his own most vicious enemy."?

This quote is attributed to Plato.

A man is his own most vicious enemy. - Plato

"A man is his own most vicious enemy."

Plato

Philosopher Ancient Greek 428–348

"The only true wisdom is in knowing you know nothing."

"The measure of a person is what they do with power."

"We are not makers of history. We are made by history."

"Knowledge which is acquired under compulsion obtains no hold on the mind."