Aristotle's ''On Interpretation'', a centrepiece of his logic, studies the relationship between conflicting pairs of statements. The first eight chapters, studied here, explain what statements are; they start from their basic components, the words, and work up to the character of opposed affirmations and negations. The 15,000 pages of the ancient Greek commentators on Aristotle, written mainly between 200 and 500 AD, constitute the largest corpus of extant Greek philosophical writing not translated into English or other European languages. This new series of translations, planned in 60 volumes, fills an important gap in the history of European thought.