
“Would you really know what philosophy offers to humanity? Philosophy offers counsel.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XLVII: On master and slave

“He that owns himself has lost nothing. But how few men are blessed with ownership of self!”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XLII: On Values

“Non faciunt meliorem equum aurei freni.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XLI: On the god within us

“You must die erect and unyielding.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XXXVII: On Allegiance to Virtue

“You must lay aside the burdens of the mind; until you do this, no place will satisfy you.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XXVIII: On travel as a cure for discontent

“You do not know where death awaits you; so be ready for it everywhere.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XXVI: On Old Age and Death

“It was a great deed to conquer Carthage, but a greater deed to conquer death.”
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XXIV: On despising death

“What progress, you ask, have I made? I have begun to be a friend to myself.”
That was indeed agreat benefit; such a person can never be alone. You may be sure that such a man is a friend to all mankind.
Seneca is quoting Hecato.
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter VI: On precepts and exemplars