Final answer:
Hamlet's father is a restless spirit due to his murder without confession, and he is punished in purgatory, reflecting Elizabethan beliefs about the afterlife and driving the play's action.
Step-by-step explanation:
Hamlet's father, the ghost in the play Hamlet, reveals that he is doomed to suffer both in the night and the day; by night he wanders and by day he is tormented by flames as a consequence of sins he committed during his life. This state of being is a common theme in Elizabethan drama, reflecting the period's beliefs about purgatory and the afterlife. The ghost specifies that he was murdered without having the opportunity to confess his sins and seek forgiveness, which has led to his purgatorial state. Hence, Hamlet's father is a restless spirit as reflected in the lines 'Doomed for a certain term to walk the night / And for the day confined to fast in fires', for he must endure punishment until he is cleansed of his sins. This situation is indicative of the overarching theme in Hamlet, where the ghost's appearance and revelations catalyze Hamlet's actions throughout the play.