William McGuffey (1800-1873) developed "McGuffey's Eclectic Readers," perhaps the most popular series of textbooks ever published. It sold 122 million copies and was repeatedly revised until 1901. Generations of public and private school students read them.
McGuffey was a professor at the University of Virginia and also president of Ohio University. He started one of nation's first teachers' associations.
The original McGuffey Readers came in four volumes and were published in 1836. William McGuffey's brother, Alexander McGuffey, produced two more volumes the next decade. In 1879, a major revision was undertaken, one which toned down much of the Calvinism of the original books, while still very much maintaining their Christian content and world view.
The original McGuffey Readers were based in Calvinist theology, and the revised version while toning down the specifically Calvinist content, nonetheless maintained a Christian world view and acknowledged the working of God in human affairs.
In the foreword of McGuffey's Reader, 1836, he wrote:
- The Christian religion is the religion of our country. From it are derived our prevalent notions of the character of God, the great moral governor of the universe. On its doctrines are founded the peculiarities of our free institutions.
McGuffey's 5th Eclectic Reader (1879) contains a lesson entitled "Religion The Only Basis of Society" by William Ellery Channing: 
- How powerless conscience would become without the belief of a God... Erase all thought and fear of God from a community, and selfishness and sensuality would absorb the whole man. Appetite, knowing no restraint ... would trample in scorn on the restraints of human laws ... Man would become...what the theory of atheism declares him to be-a companion for brutes.
The McGuffey Readers include phonics lessons when new words are introduced, and phonics are a core part of the lessons. In the introductory section to McGuffey's First Eclectic Reader (1879), it is stated that the McGuffey Readers are especially adapted to teaching using either the phonics method, the word method, or any combination of the two.
The centrality of phonics in the McGuffey Readers is in contrast to modern primers which came into use after World War II, such as the Dick and Jane books, which use the "whole language", also known as "look-say", method.