Once the long river of thousands of miles opens, what does it mean that the waves will come for nine days?

Poet of the Tang Dynasty, Hu Zeng

Ode to the epic poem Bianshui

Once the thousand-mile long river opens, waves will come in nine days.

The golden sails have not yet fallen and the war has begun, and the melancholy dragon boat will not return.

Emperor Yang of the Sui Dynasty dug the Beijing-Hangzhou Grand Canal, which consumed a lot of manpower, material and financial resources and made the people miserable. The rebel army set off a wave of overthrowing the rule of the Sui Dynasty.