The present volume was written in response to numerous requests for a complete and definitive work on Christian spirituality. It is not an entirely new work, however, for some sections are taken substantially from The Theology of Christian Perfection by Antonio Royo and Jordan Aumann, published in 1962 by Priory Press.

Spiritual theology is both speculative and practical, but it is eminently practical because it deals with Christian life in relation to the perfection of charity. Consequently, the study of the theology of Christian perfection should proceed scientifically and systematically, although its aim is not to produce scholars but to form holy Christians. Therefore the first part of this volume investigates the theological principles of Christian holiness; the second part deduces from those principles the general directives by which souls can be guided in their journey to the goal of the Christian life.

The theology contained in this volume is based on the spiritual doctrine of three Doctors of the Church: St. Thomas Aquinas, St. John of the Cross, and St. Teresa of Avila. Moreover, it is fully in accord with the teaching of John G. Arintero and Reginald Garrigou-Lagrange.

A final word of thanks is due to Laura Gillet, John Osman, Michael Balaria, and Sister Veronica Marie. They were most generous in contributing their time and labor in the typing of the manuscript.