The content of the readers changed drastically between McGuffey's 1836-1837 edition and the 1879 edition. The revised Readers were compiled to meet the needs of national unity and the dream of an American melting pot for the world's oppressed masses. The Calvinist values of salvation, righteousness, and piety were excluded from the later versions, though they had been prominent in the early Readers. The content of the books was secularized and replaced by middle-class civil religion, morality, and values. McGuffey's name was featured on these revised editions, yet he neither contributed to them nor approved their content.