The old knight set out a goal for himself, which he could not accomplish. He began this adventure feeling determined and anxious. He took this expedition for a very long period of time. As he advanced, he began to lose his courage and hope for himself. Soon enough, he couldn't sustain much longer, he failed to complete his objective and then he died without success.
1st Figurative Language
In the poem, a shadow fell over the knight's heart. This means that the knight began to feel discouraged. His ambition ended unsuccessfully. The knight started to lose the hope he developed as he went on with his search.
2nd Figurative Language
The knight sought help from the shadow, which told him to go "Over the mountains of the moon." This means that the knight is still far from his destination and will not succeed.