Marcus Aurelius ("Meditations")
WHAT HARMS THE SOUL
The soul of a man harms itself, first and foremost, when it becomes (as far as it can) a separate growth, a sort of tumour on the universe: because to resent anything that happens is to separate oneself in revolt from Nature, which holds in collective embrace the particular nature of all things ... The end for rational creatures is to follow the reason and the rule of that most venerable archetype of a governing state--the Universe. Book 2
LIVING WELL
If, when you finally come close to your exit, you have left behind and value only your directing mind and the divinity within you, if your fear is not that you will cease to live, but that you never started a life in accordance with nature, then you will be a man worthy of the universe that gave you birth. You will no longer be a stranger in your own country, no longer meet the day's events as if bemused by the unexpected, no longer hang on to this or that. Book 12
ON DEATH
What a noble thing is the soul ready for its release from the body, if now must be the time, and prepared for whatever follows--extinction, dispersal, or survival! But this readiness must come from a specific decision: not in mere revolt, like the Christians, but thoughtful, dignified, and--if others are to believe it--undramatic. Book 11
TO THE POINT
No more roundabout discussion of what makes a good man. Be one! Book 10