It is true greatness to have in one the frailty of a man and the security of a god.

The line contrasts human vulnerability (“the frailty of a man”) with divine steadiness (“the security of a god”) to define an ideal of greatness: remaining inwardly unshaken while still fully human. In a broadly Stoic register, “security” suggests moral and emotional stability—freedom from fear, panic, and dependence on external fortune—rather than physical invulnerability. Greatness, on this reading, is not the absence of weakness or pain, but the capacity to endure them without surrendering one’s rational integrity. The quote thus praises a kind of resilient composure: to feel the limits of mortality and yet possess a godlike firmness of mind.