Who is under The Ghost of Christmas Present's robe? Why should mankind beware these creatures?

As they travel, the Ghost ages and says his life is short‹he will die at midnight. A boy and girl, looking ragged, unhealthy, and impoverished, crawl out from his robes. The Ghost tells Scrooge they are named Ignorance and Want. He tells him to beware of them, especially the boy, on whose brow is written doom. He encourages Scrooge to deny Ignorance in himself and others. When Scrooge asks if the children have no refuge, the Ghost answers with Scrooge's previous words‹"'Are there no prisons? ŠAre there no workhouses?'"