Pathways to Bliss: Mythology and Personal Transformation
Joseph Campbell
Freud saw sex as the main driving force in people, whereas Alfred Adler believed it is the will to power. Jung integrated these two ideas and says we have both introverted (power) and extroverted (sex) drives.
When a person's primary drive fails or is insufficient, they have to depend on the secondary drive. Jung calls this reversal enantiodromia (running in the opposite direction).