What does Li Bai mean by saying goodbye to his friends at Jingmen Ferry?

Sail from Jingmen Ferry, and soon you will be with southerners.

At the end of the mountain range and the beginning of the plain, the river winds through the wilderness.

The moon rises like a mirror, and the sea clouds twinkle like palaces.

Water brings you the feeling of home. Tow your boat for 300 miles.

Note Jingmen: The mountain name is in the north of the county, Linghu Lake, south of the Yangtze River, and at the junction of Chu and Shu during the Warring States Period.

Phantom: A mirage. At sea, due to the change of air and the refraction of light, the sky changes into a scene similar to the street view of a tower.

That means I sailed far away from Jingmen to the ancient state of Chu. The mountains gradually disappeared and the Ye Ping unfolded. The river seems to flow into the vast wilderness. The moon shadow in the waves is like a mirror falling from the sky. Clouds in the sky form a beautiful mirage. I still love the river in my hometown and sent my boat all the way to Wan Li.

This poem was written when Li Bai wandered from Sichuan to Kuimen and then crossed Jingmen at the age of 25.

The first two sentences of this poem indicate that the poet will cross Jingmen to visit Chu. The second part describes what we saw when we crossed Jingmen: there are many mountains in the middle of Sichuan. Once out of Jingmen, the vast Ye Ping is in the east, and the mountains gradually disappear: the Yangtze River runs on the vast Yuan Ye and surges eastward. These two sentences are broad and magnificent, exactly the same as the ambition of young Li Bai. At night, the moon is reflected in the middle of the river, like a mirror falling from the sky; The changing clouds on the river look like a mirage. If the scene of the second couplet is a grand vision, then the third couplet can be regarded as a close-up scene, with clouds, moonlight and rivers forming a fantastic picture.

The ending is "Farewell"-the Yangtze River water flowing from my hometown Shu, like the affection of an old friend, sent me to the East. When Li Bai left Jingmen, he not only saw the scenery, but also seemed to be more open-minded than before. "The mountains are flat and the rivers enter the wild", such a vast landscape and unique brushwork can only be found in Du Fu's poems.