E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Wool-gathering.
Your wits are gone wool-gathering. As children sent to gather wool from hedges are absent for a trivial purpose, so persons in a brown study are absent-minded to no good purpose.
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But, my dear, if my wits are somewhat wool-gathering and unsettled, my heart is as true as a star.Harriet B. Stowe.