Nails driven into Cottage Walls
This was a Roman practice, under the notion that it kept off the plague. L. Manlius was named dictator (A.U.C. 390) “to drive the nail.”
Our cottagers still nail horseshoes to thresholds to ward off evil spirits. Mr. Coutts, the banker, had two rusty horse-shoes fastened on the highest step outside Holly Lodge.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894