What does the phrase "from pillar to post" mean?

Question: What does the phrase "from pillar to post" mean?

Answer: "Running from pillar to post" means to go from one thing to another without any definite purpose. It seems to be an allusion to manege, a dressage training regimen for horses. The pillar is the center of the riding area, and the posts are columns placed equidistantly around the ring.