Harnessing horse sense
My wife and I were talking the other day and she said "he doesn't have any horse sense." When we talked about it, she thought perhaps horse were sensible animals, I maintain that the phrase relates to working with horses, and if someone doesn't have any horse sense that means he doesn't have any idea about how to deal with horses.
From: Robert Brandt
I hope the person to whom your wife was referring never figures out who she was talking about ...
I would rather believe, having dealt with one or two horse dealers in my time, that horse sense refers to two-legged rather than four-legged animals. Horses, in my experience, have very little sense - which is why they're relatively easy to train. Horse dealers, on the other hand, can steal your socks without removing your shoes.
Horse trainers, on the third hand, are usually commonsensical and straightforward people, so Eric Partridge might be pointing to them in his Dictionary of Historical Slang, which says: "horse sense: Common sense, esp. if unrefined and somewhat earthy: orig. (1833) U.S.; anglicized ca 1895 as a coll."
Anyone who's worked in a stable will know just how earthy it can be - especially at mucking-out time first thing in the morning.
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