One speaks of people sometimes as being like a volcano. That would be someone inclined to have emotional eruptions, someone with a hot temperament and a lot of emotion which bursts out at any time. If one of the volcanoes is extinct, how would you interpret that?
Von Franz reads the volcano as a direct psychological metaphor for eruptive emotionality, and the extinct volcano as a psychic region in which that affective energy has been overcome or suppressed.
, The Problem of the Puer Aeternus, 1970thesis