He was of a mercurial temperament and therefore unpredictable.
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Related: unpredictable
Prev: take into account the seasons as well as any unpredictable weather. New seeds must be sown and weeds must be pulled.
Next: As I watch her chase after a squirrel, throwing her whole being into the here-and-now of an exercise that has never once ended in victory, she reminds me, too, that no matter how harsh the present or unpredictable the future, there's almost always some measure of joy to be extracted from the moment.
