Whoever it was who said, “Fortune, I have made a pre-emptive strike against you, and I have deprived you of every single loophole,” was not basing his confidence on bolts, locks and fortifications, but on principles and arguments which are available to anyone who wants them. […] For if the mind is self-indulgent, and takes the easiest courses all the time, and retreats from unwelcome matters to what maximizes its pleasure, the consequence is weakness and feebleness born of lack of exertion; but a mind which trains and strains itself to use rationality to conceive an image of illness and pain and exile will find that there is plenty of unreality, superficiality and unsoundness in the apparent problems and horrors each of them has to offer, as detailed rational argument demonstrates. (Plutarch, On Contentment, 467C)
Plutarch was a Platonist but perhaps influenced to some extent by aspects of Stoicism.
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