The wise old man appears in dreams in the guise of a magician, doctor, priest, teacher, professor, grandfather, or any other person possessing authority. The archetype of spirit in the shape of a man… always appears in a situation where insight, understanding, good advice, determination, planning, etc., are needed but cannot be mustered on one's own resources.
Jung's foundational statement defining the wise old man as the archetypal personification of spirit, activated compensatorily when the ego's own resources prove insufficient.
, The Archetypes and the Collective Unconscious, 1959thesis