Note Upon the Mystic Writing Pad

In this short essay, Freud uses the analogy of a child's toy, the Mystic Writing Pad, to explain the workings of the perceptual apparatus.

The Mystic Pad consists of a wax slab and a transparent sheet that overlays it.

Writing appears on the transparent sheet but can be erased by lifting it, leaving the wax slab receptive to new impressions.

Freud relates this model to the human mind, where the perceptual system (the transparent sheet) receives impressions, while the unconscious (the wax slab) retains them permanently.