Towards the end of the reign of Marcus Aurelius Oppian of Cilicia wrote a didactic epic of some 3,500 lines on sea-creatures and the methods of catching them, entitled Halieutica. This literary, rather than scientific, enterprise was hardly an original one, for Athenaeus, whose Deipnosophistae must have been published not long after the death of Commodus in A.D. 193, tells us that he was acquainted with five such hexametrical Halieuticas, those of Caecilius of Argos, Numenius of Heracleia, Pancrates of Arcadia, Poseidonius of Corinth, and lastly Oppian, whom he describes as τὸν ὀλίγῳ πρὸ ἡμῶν γενόμενον Όππιανὸν τὸν Κίλικα. The wider context of Oppian's work is that whole tradition in Greek of didactic epic as a merely literary exercise, which for us begins with Aratus in the early third century B.C., but which seems more precisely to have been initiated by Aratus' teacher Menecrates of Ephesus, who about 300 B.C. turned to the old Hesiodic tradition with the composition of an Erga. Aratus too was reviving an old tradition that seems to have flourished in the sixth century B.C. of versifying astronomical and meteorological lore. As is well known, his Phaenomena and also probably the Diosemeia are essentially a verse paraphrase of a treatise by Eudoxus, a treatise which already in Aratus' time did not provide the most up-to-date and reliable information. Later, whether only shortly or more than a century later, Nicander of Colophon likewise adapted, certainly in his Theriaca and perhaps also in his Alexipharmaca, the technical prose writings of a poison-expert Apollodorus. These are but two examples, and, as far as we can tell, typical ones, of what was done by a large number of poets from Aratus' time onwards for a considerable variety of poetically unpromising subjects, which, apart from astronomy, poisons and fishing, we know included astrology, medical prescriptions generally, hunting, agriculture, bee-keeping, geography, stones and the flights of birds, whilst the poetic treatment of yet other subjects, such as dicing, ball-games and swimming, is recorded by Ovid (Trist. 2. 471 ff.).