Robert McCrum in The Guardian:
William James, brother of the more famous Henry, was a classic American intellectual, a brilliant New Englander and renowned pragmatist – a celebrity in his time who coined the phrase “stream of consciousness”. He responded to the cultural and social ferment of the late 19th century with the Gifford lectures, given in Edinburgh during 1900-02. When he turned these talks into a book, James, a Harvard psychologist and the author of The Principles of Psychology, placed himself at the crossroads of psychology and religion to articulate an approach to religious experience that would help liberate the American mind at the beginning of the 20th century from its puritan restrictions by advancing a pluralistic view of belief inspired by American traditions of tolerance. Like his brother, he was obsessed by the problem of expressing individual consciousness through language; this is just one of the principal themes of The Varieties of Religious Experience.
…The idea that all citizens were equally and independently close to God sponsored among the James family the conviction that religious experience should not become confined within the narrow prison of a denomination. The same irreverence towards categories encouraged William James to adopt a high-low style that gives his writing a fresh and populist character that’s rather different from the mature style of his brother the novelist. William used his populism to suggest that any religious experience” was true if the consequences of holding it were pleasing to the individual concerned. This restatement of the American pursuit of happiness gave his audiences a new appreciation of human dignity grounded in everyday reality.