This is the first edition for nearly 150 years, taking into account a fuller range of manuscripts than either of the previous editions, of the collection of problems on natural science and medicine edited by Bussemaker in 1857 as pseudo-Aristotle, Problemata Inedita, and by Usener in 1859 as pseudo-Alexander of Aphrodisias, Problems books 3 and 4, the attribution differing in different manuscripts.