A soiled baby, with a neglected nose, cannot be conscientiously regarded as a thing of beauty; and inasmuch as babyhood spans but three short years, no baby is competent to be a joy “forever.”

Mark Twain (1835-1910) American writer [pseud. of Samuel Clemens]

“Answers to Correspondents,” Sketches New and Old (1875)
    (Source)

Ostensibly in response to a "Young Mother" who had written that her new baby was a thing of beauty and a joy forever.