Long is the way and hard, that out of Hell leads up to light.

The Killer's Message: "Long is the way and hard, that out of Hell leads up to light."

This phrase serves not merely as a note found at a crime scene but as the philosophical pillar dominating the entirety of Se7en. The moment killer John Doe leaves this note is discovered by Somerset after the 'Gluttony' case — the first of the Seven Deadly Sins — as he is examining the crime scene. This discovery is the decisive catalyst that makes both detectives realize this serial murder is not mere madness but a meticulously designed 'sermon.'

1. The Utterance Context and Expansion of Meaning

Context: Through the act of murder forcing the Seven Deadly Sins upon his victims, the killer exposes the sinful nature of humanity. The note discovered in this process hints that humans do not remain in a state of sin (hell), but can only reach true enlightenment or justice (light) by passing through that painful process.

Interpretation of the phrase: This phrase argues that 'redemption' or 'justice' are not things easily obtained. It presents a very pessimistic yet intellectual view: true justice can only be approached not through the 'comfortable light' of law and institutions, but through the 'hard way' of pain and truth.

2. The Impact on Somerset's and Mills's Perspectives

This message creates deep fractures in the opposing beliefs of the two detectives.

• Somerset's perspective (exhaustion and resignation): Somerset is a figure who has already experienced the weight of life and the futility of justice. For him, this phrase reinforces his resigned perspective that 'justice is inherently this difficult, and ultimately unresolved.' He is overwhelmed by the killer's intellectual design, acknowledging that the very process of pursuing justice is painful.
• Mills's perspective (passion and anger): Mills receives this phrase as an 'excuse.' He has a fierce will that even if justice is painful, one must catch the killer and change the world. For him, this phrase is interpreted as a challenge: 'You must not give up.'

The two detectives debate endlessly over this phrase, ultimately finding themselves in the process of searching for the most efficient and realistic methodology toward justice.

3. The Thematic Function Running Through the Entire Work

This phrase operates beyond merely revealing the killer's philosophy as a structural device of the film. The Seven Deadly Sins murders are all facets of this 'hard way.'

• The List of Sins: Through murder, the killer exposes the dark side of humanity — showing the face of 'hell.'
• The Process of Pursuit: The detectives' investigation is itself the 'hard way' of navigating through this labyrinth of sin.
• The Ambiguity of the Ending: The fact that in the film's ending the killer is not completely arrested, and justice remains incomplete and ambiguous, maximizes the message presented by this phrase: 'Long is the way and hard, that leads up to light.' It leads to the cynical conclusion that perfect justice does not exist.