"The elementary system of the moving forces of matter depends upon the existence of a substance which is the basis (the primordially originating moving force) of all moving forces of matter, and of which it an be said as a postulate (not as a hypothesis): There exists a universally distributed all-penetrating matter within the space it occupies or fills through repulsion, which agitates itself uniformly in all its parts and endlessly persists in this motion." [Immanuel Kant]