“out-with-the-old,in-with-the-new mantra”是什么意思?

“out-with-the-old,in-with-the-new mantra”是什么意思?
原文：
Beijing is a city hurtling toward a deadline as China readies for its first-ever Olympic Games.The Opening Ceremonies are only 11 days away,and the out-with-the-old,in-with-the-new mantra goes deeper than construction.