Despite their remedial effect the soul should never dare to desire such sensory apprehensions [about spiritual things] because: 1) they will diminish faith, which transcends all sensory perceptions, and in doing so will lead the soul away from the only means to union with God; 2) they will detain the soul and prevent the spirit from soaring to the invisible; 3) they will not allow the soul to attain to genuine renunciation and nakedness of spirit; 4) through her attachment to the sensory she becomes less receptive of the spirit of devotion; 5) she will lose the graces which God wishes to give her because she selfishly strains after such visions; and 6) the desire to accept the communications opens the door to the devil to deceive her with feigned communications.

The purer, simpler, more perfect, spiritual, and interior the general knowledge is – and that is how it is when it inundates an entirely clear soul that is free from any other impressions or specific knowledge – the freer and more delicate it is and therefore more apt to evade being perceived.
Saint Teresa Benedicta of the Cross, summarizing the teaching of Saint John of the Cross on sensory phenomena