Final answer:
The metaphor "the light" in the poem symbolizes the joy and illumination the speaker's loved one brought into their life. Forgetting 'the light' implies a difficult struggle to move on from the positive influences and memories of this person.
Step-by-step explanation:
The metaphor "the light" in the lines from "heart, we will forget him" can be interpreted in various ways. A common interpretation is that "the light" represents the illumination and joy that the subject of the speaker's affection brought into their life.
Just as light is necessary for sight and brings clarity, the individual brought understanding and happiness to the speaker. The metaphor suggests that the memory of these intangible qualities, like the feeling of warmth and enlightenment from this person, is difficult to forget, much like trying to forget the sensation of light once one has experienced it.
In literature, light often symbolizes knowledge, goodness, or a renewal of hope. Therefore, forgetting "the light" implies a loss of these positive experiences and a possible return to a state of darkness or ignorance. It can also be seen as an internal struggle between the desire to move on and the persistent memories of past emotions and experiences, which are as hard to dismiss as trying to unsee the light.