P6. †to pluck the grass to know where the wind sits: to interpret a situation or infer a fact by studying signs or indications. Obsolete.With reference to the practice of holding up a blade of grass to determine the direction of the wind.
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a1670 J. HacketScrinia Reserata (1693) ii. 16 No Man could pluck the Grass better, to know where the Wind sat; no Man could spie sooner from whence a Mischief did rise.