"Whether you believe in autonomous ghosts and spirits or not, it is difficult not to at least think of the spectral echoes of those whose pasts we retrace as we move through the spaces we share. As such, paradoxically, it isn’t necessarily the presence of the spirits of place that haunt us but their absence, and as long as we have the clues with which to construct them, ghosts will always be ready, just waiting to emerge."  --Richard Maclean Smith, Unexplained, p. 227