Volume I Substance contains under the heading Substance the writings of Plato Plotinus Boethius Marsilio Ficcino Tommaso Campanella Johannes Kepler Arthur Schopenhauer Friedrich Nietzsche and Feruccio Busoni. Under the heading Essence and Distinctness are found the writings of Aristotle Aristoxenus Philodemus Immanuel Kant Friedrich W.J. Schelling George W.F. Hegel Johann Herbart and Eduard Hanslick.

Carl Dahlhaus:
Ruth Katz: