Letters 98.3

A bad man makes everything bad—even things which had come with the appearance of what is best; but the upright and honest man corrects the wrongs of Fortune, and softens hardship and bitterness because he knows how to endure them; he likewise accepts prosperity with appreciation and moderation, and stands up against trouble with steadiness and courage. Though a man be prudent, though he conduct all his interests with well-balanced judgment, though he attempt nothing beyond his strength, he will not attain the Good which is unalloyed and beyond the reach of threats, unless he is sure in dealing with that which is unsure.

Seneca, Letters to Lucilius 98.3, translated by Richard Mott Gummere