I groped for this vast land with my broken palm. What is the function of the poem that begins with these two lines?

"I grope for this vast land with my broken palm", and the first two lines of the poem play a role in controlling the whole poem. It is conceivable that there is no map in the dark and humid dungeon. Therefore, "exploring this vast land with the damaged palm" can only be the surreal imagination of the psychological field, so that it can "explore" the map of the motherland in its mind. Poets use symbolic meaning, and "expanded land" is still an image. Dai Wangshu talked about the territory of China several times, just like a leaf, but it's a pity that a leaf is missing. I hope I can see the whole leaf one day. Now he takes the palm of his hand as the topic, which is obviously a metaphor for his yearning for the motherland and his closeness to him. The word "damaged" is full of blood and tears, which not only tells the story of their own suffering, but also tells the story of Japanese atrocities. There are both sympathy for the massacre of hundreds of millions of compatriots and deep thinking about the fate of the suffering motherland ... It is all this that has become an uncontrollable internal driving force, making the poet endure physical and mental pain and write this masterpiece.