Final answer:
Horace Mann, a nineteenth-century advocate for public education, said the quote. He emphasized the importance of education as a means to equalize the conditions of individuals in society.
Step-by-step explanation:
The nineteenth-century advocate for public education who said the quote, "Education then, beyond all other devices of human origin, is the great equalizer of the conditions of men, the balance-wheel of the social machinery," was Horace Mann. Horace Mann was an American educator and reformer who played a significant role in the development of the public education system in the United States during the 19th century. He believed that education was essential for social progress and equal opportunities.
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