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The wise man thinks about his troubles only when there is some purpose in doing so; at other times he thinks about other things, or, if it is night, about nothing at all.

Bertrand Russell (2015). “The Conquest of Happiness”, p.40, Lulu Press, Inc
The wise man thinks about his troubles only when there is some purpose in doing so; at other times he thinks about other things, or, if it is night, about nothing at all.