Since David's works were banned, most of what is known of him is from the writings of his contemporaries and opponents, chiefly Albert the Great and St. Thomas Aquinas. David's philosophy was that everything could be divided among bodies, minds, and eternal substances. The indivisible substrate or constituent of bodies is matter ("hyle"); of minds or souls, intellect ("nous"); and of eternal substances, God ("Deus"). These three, matter, intellect, and God, are actually one and the same. Consequently, all things, material, intellectual, and spiritual, have one and the same essence — God.