The frequency domain of mind (a mind, it must be stressed, is an unextended, massless, immaterial singularity) can produce an extended, spacetime domain of matter via ontological Fourier mathematics, and the two domains interact via inverse and forward Fourier transforms. An inverse Fourier transform converts a frequency (mind) function into a spacetime (material) function, and a forward Fourier transform does the opposite. So, mind can causally affect the material world, and matter can inform mind about its condition, its state. This is thus the long-sought answer to the world-historic problem of Cartesian substance dualism. The Ontological Self: The Ontological Mathematics of Consciousness