Final answer:
The line from 'Spring and Fall' that shows grief as self-centered is 'It is the blight man was born for,/It is Margaret you mourn for.'
Step-by-step explanation:
The excerpt from Gerard Manley Hopkins' "Spring and Fall" which describes grief as a self-centered act is "It is the blight man was born for,/It is Margaret you mourn for." This line suggests that Margaret's grief is ultimately about her own realization of mortality rather than the loss of autumn leaves, indicating a self-centered aspect to her sorrow.