This book contains wonderful, mysterious words—words concerning the Creator of the ages Himself. All Christians are baptized in His name—the name of the Father, the Son, and the Holy Spirit. In Him they have life and in Him they place their hope. Indeed, is anything more important than to strive for the knowledge of Him, for union with Him, for the constant contemplation of Him? God has not abandoned men in ignorance: He entrusted to the Church the revelation concerning Himself, manifested Himself in His creation, and revealed to Christians the path to endless growth in the knowledge of Him. To give the modern reader a glimpse into the inner life of God the Trinity is the purpose of this book.