Spiritual Theology
Ascetical and mystical theology: the three ways, the life of prayer, and the stages by which a soul in the state of grace advances toward perfection. Where the preceding tracts establish what is true and what is required, this one treats how the supernatural life actually develops.
What Spiritual Theology Treats
Spiritual theology is the science of the Christian life considered as a movement toward perfection. It presupposes everything the dogmatic tracts establish — above all the treatise on Grace, without which it has no subject matter — and it presupposes moral theology, which sets out what the Christian is obliged to do. It then asks a further question that neither of those answers: given a soul in the state of grace, bound by the commandments and possessed of the infused virtues, how does that life actually grow?
The question is not merely practical. That sanctifying grace is a real participation in the divine nature, that it admits of increase, that the infused virtues and the gifts of the Holy Ghost are genuine principles of operation — these are doctrinal claims established elsewhere on this site. Spiritual theology draws out what follows from them for a soul over a lifetime, and it does so with the same care for distinction and evidence as any other tract.
Ascetical and Mystical
The traditional division is between ascetical theology, which treats what a soul does under ordinary grace — mortification, meditation, the practice of the virtues, the deliberate cooperation of the will — and mystical theology, which treats what a soul receives when God acts and the soul is principally passive. The distinction turns on activity and passivity, not on intensity or holiness.
Where exactly the line falls, and whether crossing it belongs to the normal development of the Christian life or to an extraordinary vocation, is the central disputed question of the tract. Fr. Auguste Poulain held that infused contemplation constitutes a distinct and extraordinary order of grace. Fr. Réginald Garrigou-Lagrange argued the contrary at length: that infused contemplation, proceeding from the gifts of the Holy Ghost, lies in the normal way of sanctity and is the ordinary — though in fact rarely attained — term of a life of grace faithfully lived. The dispute is live, and both positions are held by serious Catholic theologians.
The Three Ways
The purgative, illuminative, and unitive ways are the classical framework for describing this development. The terminology descends from Pseudo-Dionysius; St Thomas gives it theological structure in his division of beginners, proficients, and the perfect, distinguished by whether a soul is principally occupied with fleeing sin, with growth in virtue, or with union with God.
They are not sequential grades to be completed and left behind, and the frontier between them is not sharp. The tradition speaks of a second conversion marking the passage from the purgative to the illuminative way, and of a third at the threshold of the unitive — each typically accompanied by a passive purification which the soul experiences as loss rather than progress. Much of the practical value of the tract lies in helping a reader recognise where such an experience is a falling away and where it is not.
Principal Reading
Garrigou-Lagrange's two-volume treatise is the fullest treatment of this tract in English, and it is hosted complete on Christian Perfection, our companion site. It argues the unity of the spiritual life as a single organic development from baptismal grace to the summit of contemplation, and it is the work that shaped twentieth-century Catholic thinking on the interior life more than any other. Begin there.
Read it on Christian PerfectionGlenn's Tour of the Summa
4 questionsGlenn's chapter-by-chapter précis of the Summa Theologica, with links to the full Latin–English text at New Advent.