CYCLE (Gr. KUK)^os, a circle)  , in astronomy, a period of time at the end of which some aspect or relation of the heavenly bodies recurs . The more important cycles are discussed in the articles CALENDAR and ECLIPSE . In physics, the term is applied to a series of operations which, performed upon a system, brings it back to its original state; Carnot's Cycle " is an example (see THERMODYNAMICS) . From the use of the word for any period at the end of which the same events recur in the same order or for any complete series of phenomena, it is used loosely of any long period of time . The name o Eaums KUKAos, the epic cycle, was given to the poems which complete the Homeric account of the Trojan War (see below) . It is this use which has given rise to the application of the term " cycle to a series of prose or poetical romances which have for a centre one subject, whether a person, as in the Alexander, Arthurian or Charlemagne cycles, or an object, such as the ring of the Nibelungenlied . In music " Song-cycle " (Ger . Liederkreis) is similarly used of a series of songs written round one subject or set to poems by the same author . Beethoven's An die ferne Gelieble (Op . 98), published in 1816, is the earliest instance . Schubert's Die schone Miillerin, Schumann's Dichterliebe and Brahms's Magelone-Lieder are well-known instances . Epic Cycle: This is a collection or corpus of lays written about 776–580 B.C. by poets of the Ionian School, introductory or complementary to the Homeric poems, dealing with the legends of the Trojan and Theban wars .

At a later date they were arranged so as to

form a continuous narrative (the Iliad and the Odyssey included), perhaps after certain alterations had been made, to fill up gaps and remove inconsistencies and repetitions . By whom, and when, they were so arranged, cannot be decided; it is possible that it was the work of Zenodotus of Ephesus, who had the care of the epic section of the Alexandrian library . In order to furnish the general reader with a comprehensive sketch of mythological history, Proclus—according to Welcker and Valesius (Valois), not the neo-Platonist, but an unknown 2nd or 3rd century grammarian, perhaps Eutychius Proclus of Siccal in Africa, one of the tutors of Marcus Aurelius (see PROCLuS) —compiled ' a prose summary (I'paµµarucij XprlvroµaOeia) 1 An objection to this view is that according to the Augustan historian Capitolinus (Antoninus, 2) Eutychius of Sicca was a Latin not a Greek grammarian.of the contents of the poems, to serve as a sort of primer to Greek literature . Extracts from this are preserved in the Codex Venetus of Homer and Photius (cod . 239), according to which the epic cycle began with the union of Uranus and Ge and ended with the death of Odysseus on his return to Ithaca at the hands of his son Telegonus . • The cycle was in existence in his (Proclus's) time, and was in request not so much for its artistic merit, as for the " sequence of the events described in it." Further light is thrown on the subject by pictorial representations, intended for school use during the Roman imperial period, the most famous of which is the Tabula Iliaca in the Capitoline museum . . The expression " epic cycle " in the sense of a poetical collection does not occur before the Christian era; the word KUKAos (" cycle," " circle ") is used of a special kind of short poem and also of a prose abstract of mythological history; the adjective has the general sense of " hackneyed," " conventional," and is applied contemptuously (by Callimachus and Horace) to a particular Alexandrian school of poetry . The most important poems of the Trojan legendary cycle are the Cypria of Stasinus (q.v.); the Aethiopis and Iliou Perlis (Sack of Troy) of Arctinus (q.v.); the Little Iliad of Lesches (q.v.); the Nosti of Hagias or Agias; the Telegonia of Eugammon . To the Theban cycle belong: the Thebais or Expedition of Amphiaraus and the Epigoni of Antimachus . The Oechalias Halosis (capture of Oechalia) of Creophylus (q.v.); the Phocais (or Minya) of Prodicus; and the Danais of Cercops, although belonging to the old Homeric epos, cannot with certainty be included in the epic cycle . The names of the authors are in several cases exceedingly doubtful .