This book has been written mainly for Religious persons, in view of placing briefly before them what may be termed the science of their profession, as contained in the inspired Word proposed by Ollr Divine Master, and handed down from the early ages of Christianity through the Fathers of the Desert, and the Church, the Doctors of the Middle Ages, and the Saints and Spiritual writers of later date, to our own times. For, although it be certain that not the hearers of the Law are just before God, but the doers of the law shall be justified, "we are none the less admonished that he that hath looked into the perfect law, and continued therein, not becoming a forgetful hearer, but a doer of the work, this man shall be blessed in his deed.The principal scope of the Treatise is to show that the whole work of our perfection is reduced to the development of the one central virtue of LOVE, namely, the habit of Divine Charity, as being the spring of our actions, and the soul of the virtues in the supernatural order; on which all the laws of God rest, wherein they are all contained, and to the perfection of which they all tend. And, further, to bring forward the important and practical teaching of S. Thomas, and S. Bonaventure, that the Spirit of God working in us through the medium of His own virtue of love; thus governing us according to our nature, which moves by means of love, freely, readily, and sweetly.Doubtless, the tendency of our day is rather to extroversion than introversion. But seeing that the operations of man follow his nature, according to the well-received adage of the schools, if the outer works of life are to be done according to God," must not the inward springs of action in mind and heart be first formed according to Him, by means of His Divine wisdom and love? Let it not, therefore, be said that attendance to the interior is incompatible with the requirements of outer life. Rather let it be acknowledged that human life is lamentably disordered-out of order to its end-and that souls must be made to return again (as the Prophet of old cried) to the inmost heart, the spring of spiritual life and action- Return, transgressors, to the heart." If the exterior is to be reformed, the interior must be reformed: nor IS there any better way of securing right order, justice, fidelity to duty, and Charity to God and to men, than by going to the root of action, which is love. As the spring of the watch regulates the movement of the hands, so the love of God regulates the works of life: and orders the soul securely to its eternal life: since Charity, affective and effective, is God's own life, and the everlasting life of the Blessed in heaven; and IS begun in time, to be consummated in eternity.