A reprint of Evelyn Underhill's timeless study on the the nature and principles of worship and the main forms in which they find expression in Christianity. In the belief that religious experience is the starting point of theological reconstruction,the author analyses here the characteristics, principles and nature of how man relates to God. The way and degree in which ritual, symbol, sacrament and sacrifice become part of worship is also examined and, subsequently, its principles are illustrated, as embodied in the main types of cults.