What does "ebb and flow" mean?

Praise: Zhang Juzheng is versatile and courageous. God's influence on the early government, ups and downs, can not be said to be non-dry. And the power of the handle, a few in the shock of the Lord, died behind the disaster. "Book" says that I don't want to spoil my success, but I can be warned!

Mitchell's comment said: "Zhang Juzheng is familiar with and aware of the changes caused by the times, and dares to take on state affairs. In the political situation in the early days of Shenzong, the declining and decaying laws and regulations system was restored and revitalized. It cannot be said that he is not a practical and helpful person. However, because his power was so powerful, it almost threatened the emperor, and as a result, disaster came after his death. Shangshu said: "I don't want to rely on the favor and benefits of the emperor as my own success."