time flies like an arrow
A classical proverb expressing the swift passage of time. The form 流るる is an archaic attributive form of 流る (modern 流れる). Used in literary or reflective contexts.
Time flies like an arrow; before I knew it, ten years had already passed.
Another classical proverb with the same meaning, literally 'time flies like an arrow'. 歳月流るる如し emphasizes the flowing nature of time, while 光陰矢の如し emphasizes its speed.
A classical Japanese proverb. The exact origin is uncertain, but it reflects a common East Asian metaphor for the passage of time.