Seneca quote

From Dialogues and Essays:

`Why do many reversals of fortune happen to good men?' Nothing bad can happen to a good man: opposites do not mix. Just as the vast number of rivers, all the rain that falls in showers from above, and the massive volume of mineral springs do not alter the taste of the sea, do not even moderate it, so adversity's onslaughts are powerless to affect the spirit of a brave man: it remains unshaken and makes all events assume its own colour; for it is stronger than all external forces. I do not mean that he is insensible to those forces but that he conquers them, and as a man who in all else is calm and tranquil of mind he rises to face whatever attacks him. All adversity he regards as a training exercise.