A passage from Marcus Aurelius
Marcus Aurelius, Meditations 3.2
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We ought to observe also that even the things which follow after the things which are produced according to nature contain something pleasing and attractive.
Related passages
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Take away thy opinion, and then there is taken away the complaint, 'I have been harmed.' Take away the complaint, and the harm is taken away.
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If you are distressed by anything external, the pain is not due to the thing itself, but to your estimate of it; and this you have the power to revoke at any moment.
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Your present opinion founded on understanding, your present conduct directed to social good, your present disposition contented with everything that happens — that is enough.