Not the least of the phenomena contributing to the current renewal of the life and spirit bf the Catholic Church has been the liturgical movement. Indeed, many observers wilt contend that it was the liturgical revival that first sparked the whole process of probing and searching that finally issued in the Second Vatican Council and the new "spring" of the Church. It is a fact, at any rate, that one of the Council's most striking achievements has been the promulgation of a Constitution on the liturgy. Here the renowned French Oratorian, Pere Louis Bouyer, has examined the basic principles of this Constitution, and, with scholarly lucidity, now explains the practical effects of this remarkable statement of the Church's belief.