After years of friendship and admiration, Jung said to Freud: ‘Let me enjoy your friendship not as one between equals but as that of father and son.’ A dangerous thing to say to the man who invented the Oedipal complex... Freud and Jung had a famous falling-out – but after such a close relationship, what could have caused their dramatic estrangement? This is the second instalment of Aeon’s original series, ‘Philosophy Feuds’: stories of the spats between the world’s greatest thinkers, the big id