Aristotle's theory of causation places causes into four types: material cause, formal cause, final cause, and efficient cause. Material cause, as defined by Aristotle, is "that out of which a thing comes to be and which persists, ... e.g., the bronze of the statue, the silver of the bowl ..." He defines formal cause as "the form or the archetype, i.e., the statement of the essence ..." Final cause is defined by Aristotle as "that for the sake of which" a thing is done. He defines efficient cause as "the primary source of change or coming to rest; e.g., the man who gave advice is a cause, the father is the cause of the child, and generally what makes of what is made and what causes change of what is changed." The author of this chapter shows that by none of these definitions of cause can the HIV virus be viewed as the cause of AIDS. Science can only claim that the HIV virus is statistically linked with AIDS. 22 notes.