What is the theme in Mother Teresa, in My Own Words by Mother Teresa?

One of the chapters of Mother Teresa: In My Own Words is titled "Christ in the Poor" in which Mother Teresa directly expresses a theme that is present in nearly all the other chapters. Teresa takes the Christian Scriptures to teach that when she performs acts of service for the needy and the poor, she literally performs these acts for Jesus Christ. When Jesus says, "What you do for the least of these, you do for me." Teresa takes him to mean something close to literal, in that Christ is somehow present in a particularly potent fashion within the lives of the suffering and poor.