Taking his own experience with color-blindness as a starting point, Wu considers Rembrandt's ruminations on light, and finds inspiration in the butterfly's play of light and shadow for his own poetical and philosophical reflections.
如＜趁著有光＞一篇談「眼」，作者以自己「色弱」所產生的色彩經驗出發，談到畫家林布蘭對「光」的反芻，進而從蝶翅翩翩閃過的光影中，思索哲學裡有關「詩化」的命題。