Now my days are swifter than a post. Life slips away so fast that before it is well begun, it is ended. Job compares it to the swift passage of the trained runner, or messenger, who carried despatches for kings and other great personages in the olden times (see 2 Chronicles 30:6; Esther 3:13; Esther 8:10, Esther 8:14).
Herodotus says of the trained runners employed by the Persians, "Nothing mortal travels so fast as these Persian messengers" (Herod; 8.98). There is abundant evidence of the employment of such persons in ancient Egypt.
They flee away, they see no good. It seems to Job that his prosperity (Job 1:2-5) was only for a moment. He scarcely could look on it before it was gone.