 In this case, Reichenbach said that C is causally between A and E. We might say that C is an intermediate cause between A and E, or that C is a proximate cause of E and A a distal cause of E. For example, unprotected sex (A) causes AIDS (E) only by causing HIV infection (C). Then we would expect that among those already infected with HIV, those who became infected through unprotected sex would be no more likely to contract AIDS than those who became infected in some other way.