The Society of Bollandists lent me, for a liberal length of time, various rare books. I shall indeed be proud if my Appendix wins their approbation, since it deals with subject-matters and methods in which they are past-masters. Father Sticker’s pages on St. Catherine, in their Acta Sanctorum (1752), are certainly not satisfactory; they are, however, quite untypical of the Bollandists’ best work, or even of their average performances.
My obligations in my Psychological and Philosophical Parts First and Third are still more numerous and far more difficult to trace. Indeed it is precisely where these obligations are the most far-reaching that I can least measure them, since the influence of the books and persons concerned has become part of the texture of my own mind.
But among the great religious spirits or stimulating thinkers of Classical and Patristic times, I am conscious of profound obligations to Plato generally; to Aristotle on two points; to St. Paul; to Plotinus; to Clement of Alexandria; and to St. Augustine. And the Areopagite Literature has necessarily been continuously in my mind. Among Mediaeval writers St. Thomas Aquinas has helped me greatly, in ways both direct and indirect; Eckhart has, with the help of Father H. S. Denifle’s investigations, furnished much food for reflection by his most instructive doctrinal excesses; and the extraordinarily deep and daring spirituality of Jacopone da Todi’s poetry has been studied with the greatest care.
The Renaissance times have given me Cardinal Nicolas of Coes, whose great Dialogue de Idiota has helped me in various ways. And in the early post-Reformation period I have carefully studied, and have been much influenced by, that many-sided, shrewdly wise book, St. Teresa’s Autobiography. Yet it is St. John of the Cross, that massively virile Contemplative, who has most deeply influenced me throughout this work. St. Catherine is, I think, more like him, in her ultimate spirit, than any other Saint or spiritual writer known to me; she is certainly far more like him than is St. Teresa.
Later on, I have learnt much from Fénelon’s Latin writings concerning Pure Love, of 1710 and 1712; together with Abbé Gosselin’s admirably lucid Analyse de la Controverse du Quiétisme, 1820, and the Jesuit Father Deharbe’s solid and sober die vollkommene Liebe Gottes, 1856.
Among modern philosophers I have been especially occupied with, and variously stimulated or warned by, Spinoza, with his deep religious intuition and aspiration, and his determinist system, so destructive because taken by him as ultimate; Leibniz, with his admirably continuous sense of the multiplicity in every living unity, of the organic character, the inside of everything that fully exists, and of the depth and range of our subconscious mental and emotional life; Kant, with his keen criticisms and searching analyses, his profound ethical instincts, and his curious want of the specifically religious sense and insight; Schopenhauer, with his remarkable recognition of the truth and greatness of the Ascetic element and ideal; Trendelenburg, with his continuous requirement of an operative knowledge of the chief stages which any principle or category has passed through in human history, if we would judge this principle with any fruit; Kierkegaard, that certainly one-sided, yet impressively tenacious re-discoverer and proclaimer of the poignant sense of the Transcendent essential to all deep religion, and especially to Christianity, religion’s flower and crown; and Fechner, in his little-known book, so delightfully convincing in its rich simplicity, die drei Motive und Gründe des Glaubens, 1863.
Of quite recent or still living writers, two have been used by me on a scale which would be unpardonable, had the matters treated by them been the direct subjects of my book. In Part First whole pages of mine are marked by me as little but a précis of passages in Dr. Eduard Zeller’s standard Philosophy of the Greeks. I have myself much studied Heracleitus, Parmenides, Plato and Plotinus; and I have, also in the case of the other philosophers, always followed up and tested such passages of Zeller as I have here transcribed. But I did not, for by far the most part, think it worth while, on these largely quite general and practically uncontested matters, to construct fresh appreciations of my own, rather than to reproduce, with due consideration and acknowledgments, the conclusions of such an accepted authority. And already in Part First, but especially in Part Third, I have utilized as largely, although here with still more of personal knowledge and of careful re-examination, considerable sections of Professor H. J. Holtzmann’s Lehrbuch der Neutestamentlichen Theologie, 1897—sections which happen to be, upon the whole, the deepest and most solid in that great but often daring work. The same Professor Holtzmann is, besides, a most suggestive religious philosopher; and his penetrating though very difficult book Richard Rothe’s Speculatives System, 1899, has also been of considerable use.
Other recent or contemporary German writers to whom I owe much, are Erwin Rhode, in his exquisite great book, Psyche, 2nd ed., 1898; Professor Johannes Volkelt, in his penetratingly critical Kant’s Erkenntnisstheorie, 1879; Professor Hugo Münsterberg, in his largely planned although too absolute Grundzüge der Psychologie, Vol. I., 1900; Professor Heinrich Rickert, in his admirably discriminating Grenzen der naturwissenschaftlichen Begriffsbildung, 1902; and also two friends whose keen care for religion never flags—Professors Rudolf Eucken of Jena and Ernst Troeltsch of Heidelberg. Eucken’s Lebensanschauungen der grossen Denker, 1st ed., 1890; der Kampf um einen geistigen Lebensinhalt, 1896; and the earlier sections of der Wahrheitsgehalt der Religion, 1902, have greatly helped me. And Troeltsch’s Grund-probleme der Ethik, 1902, has considerably influenced certain central conceptions of my book, notwithstanding the involuntary, rough injustice manifested by him, especially elsewhere, towards the Roman Church.
Among present-day French writers, my book owes most to Professor Maurice Blondel’s, partly obscure yet intensely alive and religiously deep, work L’Action, 1893; to Dr. Pierre Janet’s carefully first-hand observations, as chronicled in his Etat Mental des Hystériques, 1894; to Monsieur Emil Boutroux’s very suggestive paper Psychologie du Mysticisme, 1902; to various pregnant articles of the Abbé L. Laberthonnière in the Annales de Philosophie Chrétienne, 1898-1906; and to M. Henri Bergson’s delicately penetrating Essai sur les Données Immédiates de la Conscience, 2nd ed., 1898.
And amongst living Englishmen, the work is most indebted to Professor A. S. Pringle-Pattison, especially to his eminently sane Hegelianism and Personality, 2nd ed., 1893; to Professor James Ward, in his strenuous Naturalism and Agnosticism, 1st ed., 1899; to the Reverend George Tyrrell’s Hard Sayings, 1898, and The Faith of the Millions, 2 vols., 1901, so full of insight into Mysticism; and, very especially, to Dr. Edward Caird, in his admirably wide and balanced survey, The Evolution of Theology in the Greek Philosophers, 1904.