The “point” and the “line” represent visual images which remain invariant under a wide range of conditions. The same is true of the visual images associated with the propositions of Euclid; hence the propositions themselves are communicated over long periods of time and between widely separated cultures and races. It sometimes helps to illuminate an analytic problem by speaking of a characteristic as appearing to the patient a “ghost of the past”. The infant experiences what may be called ghosts of the future. Such locutions are possible to adult investigations for maturity provides terms born of experience together with facility in their manipulation. Transformation may be a transference of characteristics from one situation to another, from one medium to another, a rigid motion, or a projective transformation. The transformation cannot occur without an emotional experience such that its proper model is the scene of violence at the crossroads at Thebes.