Memento mori literally means "Remember you must
die". The early Puritan settlers were particularly aware of death and fearful
of what it might mean, so a Puritan tombstone will often display a memento
mori intended for the living. These death's-heads or skulls may strike us as
ghoulish, but they helped keep the living on the straight and narrow for fear
of eternal punishment. In earlier centuries, an educated European might place
an actual skull on his desk to keep the idea of death always present in his
mind.
Prayer card to accompany this tradition: http://filefactory.com/file/6wfp1ty6318l/Remember-oh-soul.jpg
