Final answer:
The phrase 'Some moulder'd steps lead into this cool cell' is a metaphor for the passage of time.
Step-by-step explanation:
The phrase 'Some moulder'd steps lead into this cool cell' is a metaphor for the passage of time. The word 'moulder'd' suggests decay and implies that the steps have been untouched for a long time. The phrase 'lead into this cool cell' creates an image of entering a hidden or forgotten place, which further emphasizes the idea of the steps leading to the past. This metaphorical description conveys the sense of time passing and the remnants of the past.