"Nick and the Candlestick" is written from the perspective of a woman who has given birth. She talks about the difficulties of motherhood, comparing her experiences to those of a miner.
The speaker uses vivid sensory imagery to evoke the cold, dark, unsettling ambiance of the cave, which she compares via metaphor to a womb. She describes dripping water and swooping bats. The overall impression created is that the speaker is navigating an unknown, frightening space, and that she does so alone. However, it soon becomes clear that she has help from a candle, which lights her way. Soon after mentioning the candle, she addresses her child, suggesting that the candle is in fact a metaphorical representation of the baby.
The speaker addresses the child with a blend of fondness and awe, noting that he continues to lie in the same position he lay in before being born. She assures him that the pain of the world does not belong to him, and tells him how she has decorated their shared, cave-like space with "roses" and "soft rugs" in order to comfort him and shield him from the world.
Finally, the speaker tells her son that even if the world was ending, she would be comforted by his presence. Her baby represents hope and warmth, and she even describes him as "the baby in the barn," an allusion to Jesus. With this allusion, the speaker suggests that her child was born to offer comfort and salvation, even in dark or frightening places and times.