Clocks have their own aura. They quantify invisible and unstoppable time. And mechanical clocks have also interesting audio properties - in fact they scan time through their repetitive sounds. Coincidence Engines is a series of artworks by [The User], a group that became famous because of their Symphony for Dot Matrix Printers, composing beautiful melodies with the noisy first generation of printers for computers. The Coincidence Engines series is conceived as an homage to the György Ligeti's Poème Symphonique, where metronomes were used not for specifying tempo, but as proper musical instruments. Here clocks are assuming the same role, setting the pace of the spectator's perception. The first of the two artworks arranges a large number of asynchronous clocks in a sort of arena for a single listener, generating an almost overwhelming ticking (and so timing) environment. The second uses specially-modified clocks "articulating audio-visual compositions by programming....the clocks' ticking behaviour." They become then instruments, singing a different time.