* The death of his father: Hamlet is deeply grieving the loss of his father, King Hamlet, whom he admired and loved. His father's death is a profound personal loss and a blow to the natural order of things. He feels a sense of betrayal and injustice.
* His mother's hasty remarriage: Hamlet is disturbed by his mother Gertrude's rapid marriage to his uncle, Claudius, who becomes the new king. This is seen as a violation of social and familial norms and a betrayal of his father's memory. He feels abandoned and replaced.
* Claudius's perceived usurpation: Hamlet believes Claudius has not only taken the throne but also his mother's love, further amplifying his feelings of anger and injustice. He feels a sense of responsibility to avenge his father's death and restore order to the kingdom.
* The ghost's revelation: Hamlet's encounter with his father's ghost, who reveals that Claudius murdered him, sends Hamlet spiraling deeper into despair and fury. The knowledge of his father's murder adds a layer of complexity to his grief and a sense of urgency to his need for justice.
* Existential questioning: The play's opening lines, "O, that this too too solid flesh would melt," reflect Hamlet's deep contemplation of life and death. The loss of his father has plunged him into a world of philosophical questioning about mortality, the meaning of life, and the nature of reality.
Hamlet's initial upset is not simply a matter of grieving. It is a profound emotional and intellectual crisis that forces him to confront questions of duty, revenge, justice, and the very essence of existence. This is what makes Hamlet such a compelling and enduring character.