Since man first became aware of his existence, time has been one of his primary obsessions. While our watches and clocks remind us every day of this permanent and ineluctable flow, with a precision that is now atomic, it has not always been so. In this conference we retrace the epic of humanity's quest to master time and its measurement. From Mesopotamian clepsydras to atomic clocks, via Egyptian sundials and the discovery of quartz, mankind has drawn on its greatest geniuses, mathematicians, physicists, craftsmen and astronomers to enslave this time which will always elude us.