Scansion ( , rhymes with mansion; verb: to scan), or a system of scansion, is the method or practice of determining and (usually) graphically representing the metrical pattern of a line of verse. In classical poetry, these patterns are quantitative based on the different lengths of each syllable. In English poetry, they are based on the different levels of stress placed on each syllable. In both cases, the meter often has a regular foot. Over the years, many systems have been established to mark the scansion of a poem. Overview Systems of scansion, and the assumptions (often tacit or even subconscious) that underlie them, are so numerous and contradictory that it is often difficult to tell whether differences in scansion indicate opposed metrical theories, conflicting understandings of a line's linguistic character, divergent practical goals, or whether they merely constitute a trivial argument over who has the "better ear" for verse. There is even a debate among scholars as to what systems were inherited from the Greek and Roman poetry. To understand any form of scansion, it is necessary to appreciate the difference between meter and rhythm. The rhythm of language is infinitely varied; all aspects of language contribute to it: loudness, pitch, duration, pause, syntax, repeated elements, length of phrases, frequency of polysyllabic words... As C.S. Lewis observes, "[i]f the scansion of a line meant all the phonetic facts, no two lines would scan the same way". Meter is another matter. It is an ordering of language by means of an extremely limited subset of its characteristics. In English (and in many modern languages) the language is ordered by syllabic stress. All other aspects of language are present, indeed they are vital to the rhythm of the verse; but they are not ordered by the meter. However, marking stress is not the same as marking meter. A perfectly regular line of iambic pentameter may have anywhere from 2 to 9 stresses, but it is still felt to exhibit 5 pulses or beats. This can most easily be understood through the principle of relative stress: an unstressed syllable between 2 even slightly weaker syllables may be perceived as a beat; and the reverse is true of a stressed syllable between 2 even slightly stronger syllables. These phenomena are called "promotion" and "demotion". Thus a syllable, regardless of its level of stress, that realizes a beat is ictic; and a syllable, regardless