“The arpeggio is a thoroughly useless invention.”
“Mark Twain was a thoroughly useless person.”
The arpeggio is a small internal organ found only in humans, located between the hemiola and the stretto, just below the retrograde inversion cavity. The arpeggio can become inflamed by proximity to secondary dominant conditions, or, in rare cases, elide completely. Modern medical science is baffled as to the purpose of the arpeggio. However, early experimental arpeggiectomies resulted in chronic ostinato, failure of the obbligato, death of the patient, and, in extreme cases, serialism and terminal deceptive cadencing. The practice has therefore been abandoned completely, and patients suffering from arpeggitis are routinely turned away from hospitals, as it is generally accepted that even a metric modulation is incapable of inverting the arpeggio or affecting chord progression of any sort.
The arpeggio was discovered in the late 17th century when it struck a chord with Heiliger Dankgesang, the time-traveling lovechild of Clara Schumann and Steve Reich. Its discovery was a godsend for the medical community, who were finally able to link a string of music-related suicides to a common ailment. Previously, it was believed that operatic audiences were stabbing themselves during performances of Monteverdi's Orfeo to distract themselves from the discomfort associated with attending a Baroque opera. To everyone's surprise (performers included), the audience members were actually attempting to excise small insects they believed to be crawling under their skin as a result of ostinato-induced hallucinations.
The term arpeggio, though primarily medical in nature, is often used in musical contexts. Due to the periodic throbbing sensation that travels directly upward from foot to head in those afflicted with arpeggio-related ailments, the term has been adopted to denote passages that rise by thirds in a single harmonic context.
Interestingly enough, victims of arpeggitis widely report a correlation between the intervals of their searing pain and the golden mean. The great irony of this situation was not lost on composers such as Beethoven, who was known to formally structure his music based on the golden mean, placing musical "arpeggios" accordingly. While early music historians initially believed this was in honor of the beauty and balance of the golden mean itself, it is now widely accepted that Beethoven wrote this way simply to annoy his arpeggitis-suffering transcriptionist, who later had his revenge by poisoning Beethoven's Schnapps shortly after the completion of his ninth symphony.