Journal of the History of Ideas

INTRODUCTION

The concept of the ground of the soul—Grund der Seele or fundus animae—is well established within the theological tradition:¹ for example, the "depths of a person's heart" (βάθος καρδίας ἀνθρώπου) is featured in Judith 8:14 in the Septuagint translation. In the Greek-Latin patristics, Diadochos of Photike uses the phrase "depths of the soul" (βάθος τῆς ψυχῆς) to indicate where God's love resides upon baptism,² while Augustine of Hippo speaks of a "secret recess of the mind" (abditum mentis) where the true image of God dwells.³ [End Page 51]

The word "ground" originally meant the lowest surface of a body.⁴ The Middle High German poets, who tended to use the genitive to amplify certain phrases, saw in this term a semantic potential for metaphorical use.⁵ Hence, for instance, the phrase grunde des herzen (ground of the heart) intensified the word herz, thereby implying a higher degree of intimacy. When Meister Eckhart appropriated the term, linking it to the scriptural images of the well of living water and the good soil in the parable of the sower,⁶ the ground or the luminous vertex⁷—synonymous terms because of the overlap of depth and height in spiritual matters⁸—began to be regarded as the divine and uncreated essence of the soul.⁹

While in Eckhart the grunt der sêle is unknowable and inexpressible in its inaccessibility, in Johannes Tauler the notion takes on a more ascetic nuance: rather than the essence, the ground seems to be a place into which one can withdraw to listen to the word of God, who speaks in a person's innermost core.¹⁰ In the later mystical literature influenced by Tauler (Hendrik Herp; Maximilianus Sandaeus; Louis De Blois), what had been understood as the essence of the soul thus becomes progressively spatialized, as if the ground or the vertex were a real topographical location. The fundus animae consequently became the highest or deepest level of the soul, where man can be one with God.¹¹ Loosened from its ontological background, the fundus animae enjoyed currency in the ethical vocabulary of the early [End Page 52] modern age, particularly among the French moralists, as the quintessence of what is inscrutable and mysterious in the soul—as the hidden root of our affections.¹²

The idea of fundus animae experienced a decided renaissance in eighteenth-century Germany. In secondary literature, Alexander Gottlieb Baumgarten is widely regarded as the first to use the term fundus animae, in his Metaphysica (1739), to designate the collection of obscure (hence unconscious) perceptions in the soul.¹³ While some commentators have pointed out that the notion of fundus animae has a long theological history preceding Baumgarten,¹⁴ the genesis and the reasons for its psychological revival in the Aufklärung have heretofore remained generally unexplored. What caused a formerly mystical notion to become a key concept in the theory of the mind and aesthetics in eighteenth-century German rationalism? How and why did the luminous abode of God in the soul morph into the dark basement of the unconscious?

With the present essay, I aim to answer these questions. Starting with Leibniz, I investigate, on the one hand, his metaphysical conception of the fundus animae and the subsequent empirization of the notion culminating with Sulzer; on the other, I bring to the fore the fruitful tension between mystical and rationalist elements that constitutes a relevant if overlooked aspect of the development of eighteenth-century psychology.¹⁵ Through the study of the conceptual reframing of the fundus animae from this double [End Page 53] and intertwined perspective, I will emphasize the progressive psychologization of the notion and its role in legitimizing obscure knowledge within the gnoseological agenda of the German Enlightenment. In this way, I intend to contribute to a more insightful understanding of the intellectual history of the unconscious in the eighteenth century, of which the fundus animae is broadly recognized to be a crucial element.¹⁶ More specifically, I will draw on new evidence about how the fundus animae proved to be a key concept to...