WHEN did you last inhale? Was it while reading this sentence? Or this one? Respiration is constant and critical and just below the threshold of awareness . . . until it is lost. Then it becomes all in all. Respiration fascinates me. In English we have mostly forgotten the connection between breath and spirit, but it pervades ancient and medieval theology. Greek pneuma and Latin spiritus can be translated prosaically, viscerally, biologically as air in the lungs. Greek psyche and Latin anima were used for ‘breathing thing’ or ‘living thing’ (including animals and sometimes plants) as well as ‘soul.’¹ The ambiguity lingers in the English language. Inspiration still evokes both bodily inhalation and divine indwelling. Expiration still describes both exhalation and death. But what about the two together? What about re-spir-ation, the coming and going of breath? This first caught my attention as an undergraduate. Majoring in biochemistry and the study of religion, I often had to switch gears very quickly. One day, I found myself marvelling at the central place of respiration in both fields: breath moving in and out of the body and Spirit moving in and out of the world. The Holy Spirit will be familiar to Christians: the breath of God. In the beginning, it moved over the face of the deep.² It inspired Adam in the Garden and the Church at Pentecost.³ Biological respiration should also be familiar, the movement of oxygen in bodies. It is, after all, as close as your breath. But few of us know the scientific details. Biologists note respiration at three levels. First, physical ventilation: living bodies bring air in and push it out again. This is the oldest and most common definition. Second, oxygen circulates within bodies, so it can reach every part. In humans, oxygen passes from lungs to blood, travels through arteries, capillaries, and veins, and then passes into cells.⁴ Waste products like carbon dioxide flow out of the body in the same way. Physiological respiration describes these two processes that get oxygen in and out of multicellular organisms. A third process, cellular respiration, describes a similar movement inside cells. Oxygen flows into mitochondria, which use it to produce energy.⁵ Although there are alternatives, aerobic respiration is the key process for plants and animals. The gas (O₂) acts as an electron acceptor, taking electrons from complex fuel molecules, just as in a candle flame.⁶ And, just like in a candle flame, this produces carbon dioxide (CO₂) as a waste product. So, oxygen empowers bodies, flowing in (as O₂) and out (as CO₂), a continuous movement. All life participates in the flow of breath in and out of bodies, a miraculous conversion of molecules and matter into motion and meaning. Physical breath – a metaphor for Grace Thinking about theology and biochemistry side by side, I became curious. If divine respiration is key to Christian life and chemical respiration is key to biological life, are they related? At first it seemed an odd, linguistic curiosity. Physical breath is a metaphor for divine grace. Christian thinkers use familiar biology – for example the growth of seeds – to explain less-familiar theology.⁷ Perhaps it was a historical accident that Greek scribes (of the Septuagint) and Latin scribes (of the Vulgate) chose these words – pneuma and spiritus – when translating Hebrew concepts (i.e., ruach and neshamah). Perhaps it was a historical accident that biologists continued to use the same terms for animal and plant processes (in the fourteenth and nineteenth centuries respectively). I can get over-excited about linguistic connections. And biology and theology speak different languages. Don’t they? Studying biology at Harvard, I gained a deeper respect for respiration. I learned more about the intricate networks of chemical reactions that underwrite life as we know it – metabolism. Two metabolic processes – photosynthesis and respiration – provide energy for the most familiar forms of life, plants and animals. My own research focused on how plants (and bacteria) convert sunlight into sugars and O₂ – photosynthesis. Plants and animals both use sugars and O₂ to fuel growth and activity through respiration. I joked that this was ‘light made manifest.’ I knew that both photosynthesis and respiration were central to understanding life on Earth, but I still didn’t think too much about the role of God’s Spirit in all of it. Then I went to seminary. Curiosity gave way to contemplation. I started to look for God’s Spirit in all times and places. I began to see all life, from the tiniest molecule to the grand arc of evolution, as moved by the breath of God. And I thought more deeply about how God put me together. For it was you who formed my inward parts;you knit me together in my mother’s womb.I praise you, for I am fearfully and wonderfully made.Wonderful are your works;that I know very well.My frame was not hidden from you,when I was being made in secret,intricately woven in the depths of the earth.Your eyes beheld my unformed substance.In your book were writtenall the days that were formed for me,when none of them as yet existed.⁸ I began to look for God’s still small voice in every aspect of my life, even in my science . . . even in my metabolism. The scribes of Psalms would not have known modern biochemistry; they must have written more abstractly. But what if divine knowledge and divine action were present in the movement of molecules? It was still only intuition, but seminary taught me to seek God, even here, in the hidden depths of biochemistry. I found the question “What is life?” profoundly important to me, both as a biologist and as a theologian. In neither role was I willing to give up asking it or claiming some part of the answer. The breath of Jesus Years passed. Other passages caught my attention. All four gospels mention Jesus’ last breath.⁹ In each case, the Greek has him yielding breath (pneuma) or simply breathing out (exepneusen). The King James translation poetically reads “gave up the ghost”. The Synoptic gospels pair this with Jesus crying out,...
