Aion, originally published in German in 1951, is one of the major
works of Jung's later years. The central theme of the volume is the
symbolic representation of the psychic totality through the concept of
the Self, whose traditional historical equivalent is the figure of
Christ. Jung demonstrates his thesis by an investigation of the
Allegoria Christi, especially the fish symbol, but also of Gnostic and
alchemical symbolism, which he treats as phenomena of cultural
assimilation. The first four chapters, on the ego, the shadow, and the
anima and animus, provide a valuable summation of these key concepts in
Jung's system of psychology.