Final answer:
The question references Dante's Inferno, specifically canto VII, but the provided excerpts do not match the request. It is essential to refer to the correct source for literary analysis of a specific canto.
Step-by-step explanation:
"Read lines 16 - 21 from canto vii at that we moved on down to the fourth crater" seems to pertain to a specific literary work, likely referencing Dante's Inferno from the Divine Comedy. However, the provided excerpts do not contain the requested lines from canto VII, and none of the excerpts relate to Dante's work directly. It's important to verify the correct text or source when dealing with literary analysis or specific line references to a poem or canto. If the student has access to the text of canto VII, they can locate the lines for their analysis or discussion.