Fall Imagery
Anytime you hear a religious poet, like Hopkins, using the word "fall," you have to assume that he or she is thinking not only of the season, but also of the "fall of man"—a.k.a. Adam and Eve eat...
Sorrow Imagery
The whole reason that the speaker is talking to Margaret is that she is crying over the dead leaves she finds in the forest of Goldengrove. The speaker then starts musing about what the real reason...