Ligeti's "Clocks and Clouds" is a relatively-short composition from 1972-1973 that takes its title from Karl Popper's 1966 philosophical essay "Of Clouds and Clocks". In this, Popper makes a compelling and easily-understood argument that scientific phenomena can be broken down into two main categories. The "clocks" are things that we can depend on such as, well, clocks. A clock can be easily measured, taken apart, and reconstructed. "Clouds", on the other hand, are things that we can only get a general, macroscopic view of -- things whose inner-workings we are unable to understand in a deterministic way.
