Early Greek theories of space developed hand in hand with theories of law, both human and cosmic. There is, for early Greek thinkers, both a law of space, and a space of law. These two normative systems merge in the development of early Greek cosmo-music theory, particularly in the cosmology of Plato. This theory will be outlined, and then looked to Xenakis, arguing that he models his own art practices with sound and space on Plato, and in particular on the role Plato gives to the demiurge. And so cities, souls, and the cosmos are all constructed according to norms which are brought together in musical theory.