The Bay Psalm Book, which was printed here in Cambridge three hundred years ago this summer, is something much more significant than a bibliographical rarity or a literary curiosity. Its early editions are, of course, choice items of Americana for collectors, and its verse, which at first sight seems so uncouth, has provoked the derision or sarcasm of unsympathetic critics who have done no more than glance at it. Unfortunately most people know little more about the book than these widely publicized facts. But the Bay Psalm Book deserves respectful consideration on other and better grounds, for it is the earliest literary monument of the English-speaking colonists on this continent; it is a key to an understanding of their religious life; and it was the fountain-head of that great stream of later American hymnody of which it is the direct spiritual ancestor.