The phrase, "to stumble at the threshold," originated in the
circumstance, that the old thresholds, or steps under the door, were
like the hearths, raised a little, so that a person might stumble over
them, unless proper care were taken. A very whimsical reason for this
practice is given in a curious little tract by Sir Balthazar Gerbier,
entitled, "Council and Advice to all Builders," 1663, in these
words:--"A good surveyor shuns also the ordering of doores with
stumbling thresholds, though our forefathers affected them, perchance to
perpetuate the antient custome of bridegroomes, when formerly at their
return from church they did use to lift up their bride, and to knock her
head against that of the doore, for a remembrance that she was not to
pass the threshold of her house without leave."