Even the finest sword plunged into salt water will eventually rust.

Although often attributed to Sun Tzu, this aphorism expresses a broadly classical idea: excellence is not self-sustaining when placed in a corrosive environment. A “finest sword” suggests innate quality, training, or virtue; “salt water” suggests conditions that steadily undermine that quality—neglect, bad counsel, corrupt institutions, or prolonged exposure to harmful habits. The point is cautionary and strategic: even superior tools and people require proper maintenance and suitable conditions, and time plus adverse surroundings can defeat raw superiority. Read this way, it aligns with strategic thinking about logistics, discipline, and the importance of conditions over mere talent.