No man knows till he has suffered from the night how sweet and dear to his heart and eye the morning can be.

The line contrasts “night” (suffering, fear, despair, or moral darkness) with “morning” (relief, safety, renewal). Its claim is experiential: only those who have endured hardship can fully perceive and value deliverance. The phrasing also echoes a Gothic sensibility—darkness as an enclosing trial and dawn as a hard-won reprieve—suggesting that gratitude and emotional depth are intensified by prior pain. In a broader ethical sense, it implies that suffering can sharpen perception and enlarge appreciation, not because suffering is good in itself, but because it changes the scale by which one measures peace and joy.