Lacuria: Occultist Philosopher and Theologian in the 19th Century (vol. I)

Vol. I: Biography and Work of Father Lacuria

Bruno Bérard

To be published by Editions de La Tarente, autumn 2024.

The book is in French – here a translation of key elements in English.

Independent thinker of theology and metaphysics during the tumultuous 19th century, Father Lacuria caused a lot of ink to flow and was picked up here and there by occultists or esotericists. It was time to closely study his life and work and definitively attest to the orthodoxy of his Catholic thought and the nature of his number mysticism. Volume I reviews Lacuria’s life and work.


  1. Introduction: A Figure in Chaos

  2. Part 1. Biography of Father Paul-François-Gaspard Lacuria

    1. Foreword
    2. Chap. I Critical Portrait of the Main Biographical Sources
    3. Chap. II Family and Childhood: 1806-1826
    4. Chap. III The First Commitments: 1826-1832
    5. Chap. IV The Beginnings of the College of Oullins: 1832-1836
    6. Chap. V “Castle Life”: 1837-1846
    7. Chap. VI The Campaign for Freedom of Education and the Printing of the “Harmonies of Being“: 1840-1846
    8. Chap. VII The Second Edition of the Harmonies and the Departure for Paris: 1846-1847
    9. Chap. VIII “Parisian Life”: 1847-1850
    10. Chap. IX The “Strange Hermit” of the Rue de Fourcy: c. 1851-1885
    11. Chap. X “The Hermit of Oullins”: 1886-1890
  3. Part 2. Panorama of the Work of Father Lacuria

    1. Foreword
  4. Section I. The Published Work of Father Lacuria

    1. Chap. XI Panorama of the Published Work
    2. Chap. XII Education
    3. Chap. XIII On Beethoven
    4. Chap. XIV Two Fairy Tales
    5. Chap. XV The “Harmonies of Being”
    6. Chap. XVI The “Spiritual and Mystical Notebooks”
    7. Chap. XVII Posthumous Publications on Astrology and Magic
    8. Chap. XVIII Miscellaneous Posthumous Publications
    9. Chap. XIX “On Infallibility by Mr Blanc-St-Bonnet”
  5. Section II. The Unpublished Work of Father Lacuria

    1. Chap. XX Panorama of the Unpublished Work
    2. Chap. XXI Deus Charitas est. God is love
    3. Chap. XXII “The Morality of Tools”
    4. Chap. XXIII “The One Way to Happiness”
    5. Chap. XXIV “Essay on the Social Problem”
    6. Chap. XXV “Cahier [Church] on the Social Problem or on Social Unity”
    7. Chap. XXVI “Anarchy” and “Apocalypse”
    8. Chap. XXVII “Mary, Queen of the Angels” and other Manuscripts on the Virgin
    9. Chap. XXVIII “On Stoicism and Christianity”
    10. Chap. XXIX “Historical Key to the Apocalypse”
  6. Section III. The Correspondence of (and about) Father Lacuria

    1. Chap. XXX Overview of the Lacuria’s Correspondence


From Mathematical Science to the Science of Numbers

If any “science disappears with the number and reappears with it”, mathematics, “where the number is exercised on itself”, constitutes a “pure science”, namely: “distinction related to unity”. Coming out “entirely from unity, [mathematics] can always be brought back to it”. For Lacuria, thus, “unity being at the center of intelligence, mathematics therefore constitutes an exact relationship with the center, that is why they are infallible”. It is also because mathematics, geometry and algebra, contain shapes and numbers which, if they are, strictly speaking, only negative limits to realities which remain inaccessible to them, are also symbols allowing access to them. Hence, for Lacuria, the role of numbers is not limited to quantitative abstraction and descriptive equations of physical laws, they are as many ancestral and universal symbols, qualitative, bequeathed by history—including pre-Christian—and present in biblical revelation.

This double meaning of numbers characterizes the difference between Plato and Aristotle, according to the mathematician Abraham Fraenkel (1891-1965): for the first “the existence of mathematical beings is independent of human thought”, for the second it is “abstract ideas of human activity”; and this same difference would exist between Leibniz and Kant: for the first there exists a “mathematica universalis, symbolic and formal, which goes beyond everything that is within the reach of human constructions and intuitions”, for the second, geometry and even the arithmetic “are linked to the forms of human intuition: space and time”. If it were necessary to choose, and Gödel will have done so explicitly, it is necessary to distinguish two problems beforehand: one of an ontological nature where realism and idealism clash, the other of an epistemological nature, on which lies the controversy between empiricism and idealism (Bouveresse). Therefore, Lacuria’s position is clear: we must not believe that numbers are cause or substance, a trap into which Pythagoras fell, he explains, when they are only form and limit. Moreover, he specifies, it is in this same trap that Fourier fell: although he was a “penetrating genius having felt the deep harmony with the being which was in mathematics”, but he falsely “proclaimed this great law that the mathematical laws were the very laws of being”. This is because, Lacuria makes it clear, “strictly speaking, it is not unity, but the idea of ​​unity that generates the idea of ​​numbers”.

Thus “mathematical certainty is always conscious, it does not add an atom to our positive knowledge”; we are anticipating here a famous formula: “Insofar as the propositions of mathematics relate to reality, they are not certain, and insofar as they are certain, they do not relate to reality” (Einstein). Moreover, Lacuria extends this same criticism to any science calling upon mathematics, which endows them with a double limit: “Astronomy, physics, chemistry are certain where they can be expressed by precise numbers, in all the rest, they are reduced to conjecture”.

Notice of publication

In the aftermath of the Great Revolution, France witnesses, during the Nineteenth Century, and apart from continuous political turmoils, the development of scientific progress, social ideologies, and new phases in the progressive evolution of the age-old strife between faith and reason. It is during this eventful period that Father Paul François Gaspard Lacuria (1806-1890) elaborates his main work : Les Harmonies de l’être, with the declared intention of bridging the gap between science and faith. Basing himself on the trinitarian doctrine of Roman Catholicism as well as on deep-reaching geometrical and mathematical analogies, Father Lacuria seeks an harmonious philosophical synthesis capable of establishing a universal knowledge, ultimately reducible to the ‘Great Unity’. The conspicuous lack of an academic monograph devoted to such an important mystical figure, whose work borders sometimes on occultism, has given birth to the present research, which attempts to retrace the French metaphysician’s biography and to give a detailed analysis of his works and of their posthumous fate.


An occulting philosopher and theologian in the 19th century: the life and work of Abbé Paul François Gaspard Lacuria (1806-1890) by Bruno Bérard.

An occulting philosopher and theologian in the 19th century: the life and work of Abbé Paul François Gaspard Lacuria (1806-1890) by Bruno Bérard.

Under the direction of Jean-Pierre Brach.

Defended on 16-01-2015 in Paris, EPHE, as part of the Doctoral School of Ecole Pratique des Hautes Etudes (Paris), in partnership with LEM Laboratoire d’études sur les Monothéismes (Paris; 1998-….). The president of the jury was Claude Rétat. The jury was composed of Jean-Pierre Brach, Claude Rétat, Paul Airiau, Jean-Pierre Laurant, Jean-Robert Armogathe, Jean-Pierre Chantin. The rapporteurs were Claude Rétat, Paul Airiau.

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