The most important part of the head (for the viewer) is the face, because the human face takes part in communication. Covering it says, in effect, 'this person is not available'. That is why it has been used so often by women. Because it is of soft material, the veil may be lifted back over the head or unclipped from one side. This is also a signal. It says 'now I am available'. So brides lift their veil at the point when they are married.