We take all things in a minor key as we grow older. There are few majestic passages in the later acts of life’s opera. Ambition takes a less ambitious aim. Honor becomes more reasonable and conveniently adapts itself to circumstances. And love — love dies. “Irreverence for the dreams of youth” soon creeps like a killing frost upon our hearts. The tender shoots and the expanding flowers are nipped and withered, and of a vine that yearned to stretch its tendrils round the world there is left but a sapless stump.

Jerome K. Jerome (1859-1927) English writer, humorist [Jerome Klapka Jerome]
Idle Thoughts of an Idle Fellow, “On Being In Love” (1886)
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The quoted line is from Longfellow, "The Ladder of St. Augustine."