“ 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 ὁ ἐπικὸς κύκλος, the epic cycle, was given to the poems which complete the Homeric account of the Trojan War (see below) . ”