Many composers have experimented with randomness (chance or indeterminism) in their compositions, including Wolfgang Amadeus Mozart, John Cage, and Iannis Xenakis. Ultimately though it is the interplay of, or balance between, unpredictability and predictability that creates aesthetically pleasing artifacts (Arnheim 1971). If an artifact is too chaotic it may be dicult to comprehend and appreciate. At the other extreme, if the artifact is too regular it may be uninteresting and boring.