In the whole history of Catholic theology there is hardly anything that is less noticed, yet more deserving of notice, than the fact that, since the great period of Scholasticism, there have been few theologians who were saints. We mean here by "theologian" one whose office and vocation is to expound revelation in its fullness, and therefore whose work centers on dogmatic theology. If we consider the history of theology up to the time of the great Scholastics, we are struck by the fact that the great saints, those who not only achieved an exemplary purity of life, but who also had received from God a definite mission in the Church, were, mostly, great theologians. They were "pillars of the Church", by vocation channels of her life: their own lives reproduced the fullness of the Church's teaching, and their teaching the fullness of the Church's life.
This is the reason for their enduring influence: the faithful saw in their lives an immediate expression of their teaching and a testimony to its value, and so were made fully confident in the rightness of teaching and acting. It also gave the teachers themselves the full assurance that they were not deviating from the canon of revealed truth; for the complete concept of truth, which the gospel offers us, consists precisely in this living exposition of theory in practice and of knowledge carried into action. "If you continue in my word...you shall know the truth" (John 8:32). "He that seeks the glory of him that sent me, he is true, and there is no injustice in him" (John 7:18). And even stronger: "He who says that he knows him, and keeps not his commandments, is a liar, and the truth is not in him" (1 John 2:4). "He that loves not knows not God, for God is charity" (1 John 4:8).
From the standpoint of revelation, there is simply no real truth which does not have to be incarnated in an act or in some action, so that the incarnation of CHrist is the criterion of all real truth (1 John 2:22; 4:2), and "walking in the truth" is the way the believer possesses the truth (2 John 1-4; 3 John 3-4, etc.).
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It was by virtue of this unity of knowledge and life that the great teachers of the Church were able, as was required by their special office, to be true lights and pastors of the Church.
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In short, these pillars of the Church were complete personalities: what they taught they lived with such directness, so naively, we might say, that the subsequent separation of theology and spirituality was quite unknown to them. It would not only be idle but contrary to the very conceptions of the Fathers to attempt to divide their works into those dealing with doctrine and those concerned with the Christian life (spirituality).
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[...] Denis [Pseudo-Dionysius] does not shrink from the conclusion that only one who is himself a "light of the world" can communicate what is sacred, can illuminate.
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The early medieval thinkers in the West, under the aegis of Augustine, did not depart from this basic concept. Anselm, himself abbot, bishop and doctor of the Church, knew no other canon of truth than the unity of knowledge and life. The same may be said of Bede, Bernard and Peter Damian. But as theology increasingly took on a "scholastic" form, and Aristotelianism burst in like an elemental force, the naive unity hitherto accepted was gravely shaken. No one would think of denying that the gain in clarity, insight and mastery of the entire field was enormous.
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[After Albert, Bonaventure, Thomas, and Scotus] The following epoch saw the disappearance of the "complete" theologian in the above sense, the theologian who is also a saint. In fact, spiritual men were turned away from a theology which was overlaid and overloaded with secular philosophy -- with the result that alongside dogmatic theology, meaning always thereby the central science which consists in the exposition of revealed truth, there came into being a new science of the "Christian life", one derived from the mysticism of the Middle Ages and achieving independence in the devotio moderna. On this byway, of course, we continue to find saints.
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[...] the means of expression at the disposal of [Francis de Sales and John of the Cross] differed from those of Ephraem, Gregory of Nyssa or Augustine. The Fathers found straightaway the appropriate dogmatic clothing for their very personal experience; everything became objective, and all the subjective conditions, experiences, fears, strivings, the "shock" in a word, were made to serve a fuller understanding of the content of revelation, to orchestrate its great themes.
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Theology and spirituality have become, as it were, each a world of its own, with hardly any point of contact, and so the saints and spiritual writers are more and more ignored by theologians. What modern treatise of theology, which adduces as its highest authority, next to the Bible, the great saints of the patristic and Scholastic ages, feels equally obliged to cite any of the three above-mentioned doctors, or to accord them equal weight, not to mention the numerous other later saints, such as John Vianney and Therese of Lisieux? Where theology is concerned, they hardly exist; they are left for "spirituality" to plunder. And spirituality hardly exists any longer for theology. We have seen that the modern saints themselves are not without their share of responsibility for this state of affairs. They are not taken seriously in theology because they themselves did not venture to be theologically minded.