Diagram by John Chris Jones. "A Transformational Route (or Evolutionary Pathway) This diagram, from Design Methods, reflects Jones' desire to represent the interrelationship of systems-level design ideas graphically" The diagram shows four horizontal groups representing the evolution of a design from the "Existing System" to "First Intermediate System (some faults removed)" to "Second Intermediate System (more faults removed)" to "Transformed System (all faults removed)" inside each group are black circles and/or squares, circles representing existing components, squares new components. First group is all circles, last group is all squares. Hope that isn't overwhelming :)
https://storage.googleapis.com/hci-social-storage/media_attachments/files/113/533/149/895/330/330/original/bc7c9a3586d0e316.jpg