The introduction considers the role of Western theological tradition in instilling particular attitudes toward the environment; the importance of St. Hildegard's writings in light of the contemporary ecological crisis; and an alternative—sonorous—meaning of ecology.

This chapter introduces the theme of viriditas in conjunction with the virginity of Mary, the virility of a generative or regenerative power (vir) evident in vegetality, tree branch (virga), and virtue. The red thread of these Latin words sharing the same root is what I call being-on-a-verge. The vegetality of the fecund verge accommodates (1) a femininity rid of its traditional associations with powerlessness; and (2) the potentiality of instilling slivers of infinity into finite existence.

Besides a series of psycho-physiological correspondences, we find in Hildegard's corpus a hagiography and a theography mapped onto parts of plants in a sort of spiritual botany. The analogies are complex, insofar as they involve particular species of plants or plant organs, psychic faculties, and chief actors in the Judeo-Christian theological drama. The unstable, fluid, shifting nature of the analogies is itself due to their modeling on vegetal existence, rather than on mineral stability. In focusing on vegetal analogies, I attempt to illuminate the substance of Hildegard's thought, as well as the method she borrows from the plants themselves.

Here I explore Hildegard's views on the symphonicity of modes of existence, of various living bodies, of the soul and the body, along with her idea of symphonic justice. I zero in on the synesthesia of viriditas and how it embraces all the senses. Counterintuitive as it may appear, the symphonic articulation of creatures in space and in time that amounts to the world of spirit (or, simply, to the world) under its ecological aspect is also vegetal. Plants, I argue, have some of the most intensely living bodies/voices, unremittingly reverberating with the elements, the seasons, and the planets, atmospheric phenomena and climates, other plants and animals. Their resonances repeatedly re-create the world.

Through a meticulous study of Hildegard's copious correspondences, I explore the notion of "sending" as another possible connection between the body and the soul, matter and spirit. Viriditas sent by God the Father through the Holy Spirit into Mary's womb supplies vegetality with messianic connotations. The soul is likewise sent into the body as the body's own power of self-re-creation, as viriditas. Various stages of plant life, such as flowering and fruition, are discussed in relation to the messianicity of vegetal existence as Hildegard comprehends it.

This chapter revolves around the paradox of "excessive heat" that signals, on the one hand, the ardency of faith and the love of God and, on the other, the effect of sin configured as ariditas, undoing the power of viriditas. I argue that the difference between the two kinds of excessive heat is folded into the distinction between the woods and wood: while timber is dry and ready to go up in flames, living trees are anything but inert matter ready to be incinerated by an external spiritual force. A growing bush is always burning with vitality, as exemplified in a vegetal-divine apparition before Moses. The woods themselves are ablaze; they are heat, which Hildegard associates with spirit. In them, solar energy is not only captured and detained but perpetually transformed in an ongoing elemental conversation with water, the earth, and the atmosphere.

Hildegard refrains from qualifying God as eternal; instead, she states that divinity has no beginning and no end. In this sense, his infinity becomes anarchic, without a clear arkhé—principle and principal, a unified point of departure that guides and controls the rest of a development. Though bordering on negative theology, this persistent reference to divine an-archy in Symphonia and elsewhere intersects with comparable assertions regarding plant life, with viriditas that disrupts a linear unfolding from beginning to end, and with finite existence as such.

Many of Hildegard's mystical visions end by recommending her readers to welcome her words with a kiss. In this chapter, I put forth an ecological model of sensing and knowing the world predicated on kissing. A kiss is markedly superficial, gliding or brushing on the surface of skin (even if it is the skin of the other's tongue), touched by the lips. In this, it diverges from knowing based on a mental incorporation, assimilation, and digestion of the known. Kissed, the words and what they conjure are not swallowed up by the knower, but loved and preserved in their independence. With Hildegard's indications in mind, I elaborate an ecological theology of kissing predicated on a sensuous and phenomenologically rich relation to human and nonhuman (plant and animal, divine and mineral) others, protected from the threat of our sharp teeth with the fleshy veil of the lips.

In the Postlude, I reflect on the intersection of musical and theologico-philosophical themes of the project; on the sonorous logos of ecology in Hildegard; and on the promises of vegetalizing the theological and philosophical canons in the Western tradition.