Roman Emperor Marcus Aurelius, a proponent of Stoicism, emphasized inner discipline and mastery over one's mind as the source of true strength and authority. His personal reflections, known as Meditations, offer timeless wisdom on self-control and rationality, guiding individuals to find peace by focusing on internal power rather than external events. Aurelius's philosophy continues to resonate, highlighting the enduring impact of his Stoic principles on personal conduct and leadership.