Spirits induce visions by means of phantasies , 1967 1967 . Much has been said about the visions of certain persons who have declared that they have seen many things , and who did see them , but in phantasy . I have been instructed about them , and it was likewise shown how they take place . There are spirits who by means of phantasies induce appearances that seem to be real . For example , if anything is seen in shadow , or in moonlight , or even in daylight , if the object be in a dark place , these spirits keep the mind of the beholder fixedly and continually in the thought of someone thing , be it an animal , a monster , a forest , or any other thing ; and so long as the mind is held in this thought , the phantasy is increased , and it grows to such a degree that the person is persuaded , and sees just as if the things themselves were there , whereas they are nothing but illusions . Such things befall those who indulge much in fancies , and are subject to infirmity of mind , and have thereby become credulous . These are visionaries .