Plotinus,
Enneads — Matter in Its Two Kinds
“ Matter, in sum, is necessary to quality and to quantity, and, therefore, to body. It is, thus, no name void of content; we know there is such a base, invisible and without bulk though it be. If we reject it, we must by the same reasoning reject qualities and mass: for quality, or mass, or any such entity, taken by itself apart, might be said not to exist. But these do exist, though in an obscure existence: there is much less ground for rejecting Matter, however it lurk, discerned by none of the senses. ”
