Self- development is an older name for the preliminary work of the Player/Initiate in the Great Game, which aims at balancing the four elements in body & mind. Yes, the mind or Psyche is a part of the body complex. Mind is the filter or cap over Existence which has to be made translucent and then transparent. Without mind -body balance there can be no journeyman level in the Mysteries, no entrance into the Garden without major disruption or imbalance to psychological functioning. Much of the so-called odd psychic phenomena encountered up to full psychotic breaks early in the Game by the unprepared is simply negativity & debris which was not removed.
Image: The Magician, RWS deck, blackout