1st Edition

Mathematics and Philosophy at the Turn of the First Millennium Abbo of Fleury on Calculus

By Clelia V. Crialesi Copyright 2025
220 Pages 15 B/W Illustrations
by Routledge

220 Pages 15 B/W Illustrations
by Routledge

220 Pages 15 B/W Illustrations
by Routledge

At the turn of the first millennium, scientific and philosophical knowledge was far from dormant. Arithmetic, with its diverse calculation techniques and number theory, served as a bridge to philosophy, theology, and the study of the physical world. Even something as simple as a series of multiplication tables could unlock a profound knowledge of both the divine realm and natural phenomena. Such... Read more

Introduction

 

Chapter 1

Abbo and His Time: European Culture and Mathematics

            1. Politics and Religious Culture

            2. Liberal Arts

            3. Mathematics

                        3.1 Speculative Arithmetic

                        3.2 Practical Arithmetic

 

Chapter 2

Victorious’ Calculus and Abbo’s Explanatio

            1. Contents of the Calculus

                        1.1 Praefatio de ratione calculi

                        1.2 Multiplication Tables

                        1.3 Supplementary Tables and Texts

            2. Victorious, scripulorum calculator: the Calculus and the Reckoning of Easter

            3. Two Hypothesis on the Arrival of the Calculus at Fleury

                        3.1 Hypothesis A: Lupus of Ferrière

                        3.2 Hypothesis B: Columbanus and the Abbey of Bobbio

            4. Abbo’s Explanatio: Manuscripts and Critical Editions

            5. Contents of the Explanatio

                        5.1 The Prologue (Section I)

                        5.2 The Theological Premise (Section II)

                        5.3 The Commentary on on Victorius’s Praefatio (Section III)

                        5.4 The Commentary on Victoriuous’s Multiplication Tables (Section IV)

                        5.5 On Qualitative Physics (Section V)

            6. The Pedagogical Aim and the Role of the Commentator

 

Chapter 3

A Theological Premise: Number, Measure, and Weight

            1. Augustine and Wisdom 11:21

            2. Claudianus Mamertus’ De statu animae

            3. Arithmetical Readings of Wisdom 11: 21: Hrabanus Maurus and John Scotus Eriugena

            4. Abbo’s Tractatus de numero, mensura et pondere

 

Chapter 4

Henology

            1. Neopythagorean Elements: Unity and the Flow of Numbers

            2. The Highest Good, individuum, and Unity

            3. The Lambda Diagram: a Quadrivial Henology

            4. Unity as Ontological Principle

            5. Unity as the Object of Arithmetic and Calculus

 

 

Chapter 5

The Composition of Reality

            1. Natural Compounds

                        1.1 The Arithmology of Natural Compounds

                        1.2 Natural Compounds and Change: the Phases of the Moon

            2. Artificial Compounds

                        2.1 The Five Kinds of Inequality Ratios

                        2.2 Two trinae regulae for Arithmetical Ratios

            3. Ontological Composition: the Case of the Earth in Genesis 1:2

            4. Division of Abstract Entities: the Case of the Units of Time

            5. Divisibility and Corporality: the Case of the vox

 

Chapter 6

Arithmetic and Calculus

            1. Fractions: Ounces and minutiae

            2. Representing Integer Numbers

            3. Calculus by Fingers or the loquela digitorum

            4. Calculus by Tables

            5. Multiplication Rules

 

Chapter 7

Physics Before the Physics

            1. The Early Medieval Concern for Natural Phaenomena

            2. Scientific Literature in the Early Medieval Fleury Area

            3. Qualitative Physics: from Astronomy to Physiology

            4. The Natural Power of Things

 

Conclusions

Biography

Clelia V. Crialesi is a Marie Skłodowska-Curie Fellow at SPHERE-CNRS (France). Formerly, she was an FWO Research Fellow at KU Leuven (Belgium) and a Mellon Fellow at PIMS (Canada). Her research focuses on premodern mathematical thought, with publications ranging from Boethian number theory to Euclidean geometry in the late medieval continuum debate.