A short definition of revelation by Roberto Assagioli:
A type of illuminative experience different from those mentioned so far is the “flash” of consciousness, often a sudden perception, of what a human being is, in which an individual experiences a revelation of himself. This revelation can have various, sometimes opposite, features and effects. The first, of a strongly positive nature, is the vision of the wonderful potentialities latent or active on the superconscious levels. They can yield a dazzling revelatory flash of the spiritual Self.
This is accompanied by a new understanding, a true comprehension, of the self and of others. The consciousness, while experiencing a sense of enlargement and expansion, is suffused by feelings of joy, goodness, love and gratitude. Even this revelation, however, if unexpected, sudden and over-intense, can produce undesirable and even unhealthy reactions. It can generate a sensation of excitation and exaltation. In cases where awareness of the difference between the spiritual Self and the personal “I” is lacking, the latter may attribute to itself the qualities and power of the former, with megalomania as the possible end product.
The other, reverse, aspect of inner illumination is the revelation of the inferior, dark features of the personality, hitherto ignored or unrecognized, or more or less negated and repressed in the subconscious. They constitute what Jung calls the “shadow”. When experienced without warning, this revelation can prove emotionally unbalancing, being often exacerbated by depressive states, fear and even despair. The prevention, or at least abatement, of such effects is responsive to a prior psychological preparation. The key to this preparation is a knowledge of depth psychology, which cushions the shock of surprise and assists the acceptance of the revelation by exposing the truth that the dark features of the personality form part of the general human condition.
Other reactions, less extreme but still damaging, can be experienced at the emotional as well as the physical level, should the nervous system not tolerate the intensity, or “voltage”, of the irruptive psycho-spiritual energies. I have written of this in my monograph, “Self-Realization and Psychological Disturbances”, incorporated in Psychosynthesis – A Manual of Principles and Techniques, (N.Y., Hobbs, Dorman & Co., 1965). Here I shall confine myself to saying that in this case, also, a preventive awareness of the different levels of human nature, as afforded by “three-dimensional psychology”, can lessen and help tolerate the reactions in question, as well as indicate the methods of eliminating them. From Transpersonal Inspiration