Between 1883 and 1909 a team of scholars led by Hermann Diels produced 15,000 pages of edited text of commentaries on Aristotle in Greek from the 2nd to the 13th Century AD; in most cases the first critical editions of these texts, and the first editions printed since the Renaissance. The 23 volumes (in 51 original fascicles) constitute a fundamental resource for the interpretation of Aristotle’s own texts, for the history of that interpretation and for the history of ancient philosophy generally - both in the periods from which they themselves derive and by their frequent references to earlier thinkers. The texts also provide evidence for the development of Greek usage in late antiquity, and are of major importance for the transmission of ancient philosophy to the Islamic world, to medieval Europe, and to the renaissance.