According to the general understanding, dark clouds represent unpleasant things, such as difficulties, setbacks, sadness, pain and so on. , will eventually disperse like a dark cloud, can't cover the beauty and light of the blue sky (a little rain rainbow, after a storm comes a calm). The sea is already very wide. In the author's eyes, no matter how wide the sea is, it is no longer wide, because this shore is connected with the other. In fact, it is not connected with the coast, but with the heart and feelings (although it is a little far away, China keeps our friendship and heaven is still our neighbor). This metaphor is very common. Let's understand for ourselves.
The dark clouds will eventually disperse and the sky will remain blue; In fact, the sea is not wide, because our hearts are connected, so this shore is connected with the other shore.