In the belief that all the great religions have similarities that confirm and differences that enrich peoples' spiritual outlook on the world, the editors inaugurated a series which they hoped would bring out the essential tenets of religion in what they perceived to be an age of doubt. The series was originally published in the 1950s and consisted of three kinds of books: translations of imaginative, devotional and philosophic works, with an introduction or commentary; reproductions of masterpieces of religious art; and background books showing the environment in which this literature and art arose and developed. The books overlap each other: Both Eastern and Western religious art often illustrates a religious text and many of the books seek the common ground in their cultural view of religion or philosophy.