The poet uses metaphor mostly to emphasize the idea that the poem is VALUABLE BECAUSE IT PROVIDES MANY THING.
In the excerpt given above, the speaker compares the poem to many things, which he do like to give to his beloved, but which he can not afford because he is poor. He compares the poem to a pot of food that keeps one warm during cold weather and it also compares it to a scarf,which provides warmness, protection and coziness.
