"I consider the puer aeternus attitude an unavoidable evil. Identity with the puer signifies a psychological puerility that could do nothing better than outgrow itself. It always leads to external blows of fate which show the need for another attitude. But reason accomplishes nothing, because the puer aeternus is always an agent of destiny."
Von Franz transmits Jung's clinical verdict on puer identification as a destined psychological impasse that reason cannot dissolve, establishing the diagnostic frame for her entire study.
, Puer Aeternus: A Psychological Study of the Adult Struggle with the Paradise of Childhood, 1970thesis