Book excerpt: Prayer is a subject that is of vital interest to Christians of all ages. We are constantly asking questions such as: What is prayer? Why should we pray? For what and for whom should we pray? How should we pray? The author provides answers to these and many other questions from the thought of a master of prayer, Saint Augustine of Hippo: over 500 Augustinian texts about prayer woven into a little summa about how to improve one's prayer life.