According to a very old tradition, Adam, the father of the human race, was buried on the spot where Our Lord died. A similar tradition has it that a sprig of the tree of life which Adam took from Paradise and planted as a lasting remembrance of his transgression in the place where he wished to be buried, became the wood from which the cross of Our Savior was fashioned. Thus the tomb of Adam was identified with the spot on the mount of Calvary on which the Cross was raised. So art has represented it for centuries, and the skull and bones of our first parents are placed there to indicate that they (and the whole race of man) receive new life through the death of Christ.
-- American Ecclesiastical Review
