Look how his lines create FORM and movement in the image.
See more about Durer here @ https://en.wikipedia.org/wiki/Albrecht_D%C3%BCrer
And more about the engraving here, @ https://en.wikipedia.org/wiki/Melencolia_I
Here are several details of the print to make it easier for you to explore the image and see his use of lines and marks.
First, here is the entire print-called "Melencolia" (created in 1514).
Here are some (actually LOTS) of details....