  Mach is also considered by Gestalt theorists to be one of their forerunners. Christian von Ehrenfels, the founder of Gestalt theory, begins his seminal 1890 paper “Über Gestaltqualitäten” by reviewing Gestalt ideas in Mach’s Analysis of Sensations. These ideas arose in the context of his research on Mach bands where he realized that the mind and senses actively contribute to sensation. The Analysis of Sensations is full of examples of this sort; its central concern is to understand the dynamic relation between our cognitive structure and experience. Our cognitive structure is itself formed through previous experience, and our current experience is structured by it in turn.