This chapter argues that three-dimensionality is a prerequisite for a space for thinking and feeling; in the psychotic experience the problem is the loss of depth or thickness through refusal of this space. R. Magritte's The false mirror is a prime example of the dialectics of space: the image is so full of ambiguity that it is impossible to say whether psychiatrics are looking at the sky situated inside the person or whether it is being reflected in the eye. In this dialectic psychiatrist Dictionary cannot legitimately talk of internal and external space, for each is a dynamic reflection of the other. In Euclidian geometry, psychiatrist can measure distance and hence differentiate between locii that lie in the same plane, but psychiatrist need post-Euclidian theory if psychiatrist are to include the notion of a space for thinking, with its tri-dimensionality, depth, and volume.