According to Evelyn Underhill, The universal mystic way, the actual process by which the mystic arrives at union with the absolute, consists of five stages.
First is the awakening, the stage in which one begins to have some consciousness of absolute or divine reality.
The second stage is one of purgation which is characterised by an awareness of one's own imperfections and finiteness. The response in this stage is one of self-discipline and mortification.
The third stage, illumination, is one reached by artists and visionaries as well as being the final stage of some mystics. It is marked by a consciousness of a transcendent order and a vision of a new heaven and a new earth.
The great mystics go beyond the stage of illumination to a fourth stage, called "the dark night of the soul". This fourth stage, experienced by the few, is one of final and complete purification and is marked by confusion, helplessness, stagnation of the will. It is the period of final "unselfing" and the surrender to the hidden purposes of the divine will.
The fifth and last stage is one of union with the object of love, the one Reality. Here the self has been permanently established on a transcendental level and liberated for a new purpose. Filled up with the Divine Will, it immerses itself in the temporal order, the world of appearances in order to incarnate the eternal in time, to become the mediator between humanity and eternity.