| Quote #4
drop like the tower sublime
"Yesterday" is a kind of pun. He means that the event literally happens yesterday: "Hey, did you hear about that tower that fell over in the Lake District?" He also means "yesterday" in that metaphorical sense of historical time.
| Quote #5
Or the unimaginable touch of Time. (line 14)
Now what’s so unimaginable about time? Old tower gets weaker, then falls over – seems pretty easy to imagine to us. Maybe it’s the particular image of the "touch," which personifies time, that we have a hard time wrapping our heads around.