It is my object here to indicate by what means and by what persons the natural development of the clairvoyant faculty may be achieved. In regard then to the subject, medium or seer, there are two distinct temperaments in which the faculty is likely to be dominant and capable of high and rapid development. The first is the nervous temperament, characterized by extreme activity of body and mind, nervous excitability, dark complexion, prominent features, and wiry frame. Types of this temperament are to be seen in the descriptions of Dante, Swedenborg, Melancthon, Edgar A. Poe and others. This type represents the positive seers.
The other temperament is of the passive type and is characterized by a full lymphatic habit, pale or delicate complexion, blue eyes, straight fine hair, small hands, tapering fingers, cold and fleshy to the touch; usually a thin or high voice and languid manner.
These two types of seers--of which there are many varieties-- achieve their development by quite opposite means. The positive seer projects the mental images by a psychic process impossible of description, but by a certain psychic metabolism by which the apperceptions of the soul are transformed into mental images of a purely symbolical nature. The psychic process of picture-production is involuntary and unconscious, but the perception of the mental pictures is a perfectly conscious process and involves the exercise of an introspective faculty. The passive seer, on the contrary, is effortless, and receives impressions by reflection, the visions coming imperceptibly and having a literal interpretation. The vision is not in this case of an allegorical or symbolic nature, as is the case with the positive seer, but is an actual vision of a fact or event which has already happened or as it will transpire in the future. Thus the positive vision consists in the projection of the mind towards the things of the soul-world, while the passive vision in the result of a propulsion of the soul-world upon the passive sense. Of the two kinds of vision, the passive is the more serviceable as being the more perspicuous and literal, but it has the disadvantage of being largely under the control of external influences and consequently of greater variability than the positive vision. It is, indeed, quite the common experience that the passive medium requires "conditions" for the proper exercise of the faculty and where these are lacking no vision can be obtained.