In old European churches, apparently, it is not uncommon for some people to bow to a blank wall when entering. This makes no sense until we realize that once there was a statue or wall painting in that spot that has been removed by "reformers" but is still remembered, centuries later.
This happens in England, writes Richard Kieckhefer in the opening of his book Theology in Stone, and in Germany. There, according to Otto Clemen writing in 1938, a wall painting of the Virgin Mary, painted over by iconoclasts, was (perhaps still is) being venerated; for many, the old religion, or at least the old religious practices, still linger. Reformers could not destroy the power of the image, a reminder of the holy.
We can never underestimate the collective memory of a community, especially when it stems from deep feelings. Such feelings are stronger than the shifting political winds of public policy. Stronger than the rational mind, which knows that excessive reverence of statues and relics can be superstitious.
The seemingly meaningless, absurd gesture of bowing to an empty wall is a way to acknowledge a sacred space where, in the words of T. S. Eliot, "prayer has been holy" --especially in old churches looked upon by many today as tourist sites.
As I read about the Dissolution of the monasteries under Henry VIII, I keep wondering about the thing unspoken by historians, because unknown: the feelings of all those dispossesed of their way of life, sent into terror from the safe haven of holy places that were sold off, destroyed, or left empty, the "bare, ruin'd choirs" that Shakespeare lamented. Religious matters always involve deep, often unspoken feelings.