Proclaimed a Doctor of the Church and justly revered for his efforts and achievements as a pastor and bishop, St. Alphonsus offers here one of the most powerful and accessible primers on the art of prayer ever written. The graces necessary for salvation cannot be obtained from God except by prayer, explains the legendary eighteenth-century saint and scholar. Indeed, the damned have been lost precisely through their failure to pray, and all the blessed have been saved by their perseverance in prayer. Unbeknownst to many, mental prayer is the only weapon sufficient to overcome every assault of the devil. Prayer is a port where we are safe in every storm, and a treasure that provides us with every good. It is only through the reflection and meditation of mental prayer that we come to know eternal truth, identify the hidden sins that keep us from salvation, and gain the inspiration of holy thoughts, desires, and resolutions. With St. Alphonsus's wise and holy advice, you'll learn not only how to master the art of mental prayer, but also: How to becomes docile and tender to the influence of grace Why God permits you to be assaulted by your enemies Why the grace of salvation is not a single grace but a chain of graces linked with that of final perseverance The key to developing confidence in your prayers The three reasons God delays granting you perseverance How prayer overcomes worries about being saved How souls in Purgatory can serve as spiritual aides for you The critical differences between mental prayer and devotional prayer Key prayers Alphonsus himself offered and his specific recommended daily aspirations What the ancient Church Fathers determined was the single most useful prayer exercise The ideal place, time, duration, and posture for prayer