Mary Baker Eddy founded a religion based on her discovery of the divine Science of Christ Jesus’ teachings. Like Jesus’ Sermon on the Mount, the teachings of this religion focus on thought. In the epigraph to her most important work, Science and Health with Key to the Scriptures, Eddy quotes Shakespeare: “There is nothing either good or bad, but thinking makes it so” (p. iii). 

Eddy points out that what we hold in thought is the most important element of our existence. It naturally follows in the practice of Christian Science that great emphasis is placed on our thinking—what we allow in and hold on to. This doesn’t involve positive thinking but includes a recognition of what is spiritually true—of the infinite good that constitutes God, Spirit, and His creation, which is wholly spiritual. 

Capitalizing Truth and Love as synonyms for God, Eddy counsels, “Beloved Christian Scientists, keep your minds so filled with Truth and Love, that sin, disease, and death cannot enter them. It is plain that nothing can be added to the mind already full” (The First Church of Christ, Scientist, and Miscellany, p. 210).