ABSTRACT
Time? There is time of the cosmos, of the earth, of the living, and of man. All these times are made of successions that men have sought to quantify with unities whose dimensions vary from million years to the nanosecond. But even from the point of view of the physician or biologist, time is not homogeneous. There are periods where change is slow and then there are events such as stellar explosions, earthquakes, the emergence of life, and of man. There is thus succession but there is also a duration stretching between events and a duration of the event itself. In a day of 24 hours there are two fundamental events that determine the duration of day and night, the rising and setting of the sun. This physicist's description is also that of a man who regards reality and distinguishes therein, in an incessant succession, present or past periods, some where changes are only slightly discernable (and we then speak of duration), and others that are outstanding events.
