The fourth line is the line of victory
Difficulty: Beginner Keywords: Strategy, Proverb
This proverb (citations of its usage needed) serves as a beginner advice that, on a common 19x19 board, pushing the opponent along the fourth line, so that the area underneath becomes his territory, is usually bad, or at least deserves to think twice about.
Taking this extreme, unrealistic example, we can understand that Black, earning three times as much territory as on the line of defeat, generally gets more compensation in this pushing battle, compared to White's influence on the fifth line.