"Man struggles upwards, water flows downwards" is a common saying. The previous sentence "Man struggles upwards" shows man's ambition and pursuit. Human nature is upward, superior to the same kind, and constantly improve themselves. "Water flows downwards" is an objective law of nature. Under the action of gravity, water will naturally flow downwards. This is an inspirational sentence, which means that if people don't work hard and struggle, they will only flow downwards like water.