Exercises in eternal delight

In The Marriage of Heaven and Hell (1790), William Blake writes:

"All Bibles or sacred codes have been the causes of the following Errors:1. That Man has two real existing principles: Viz: a Body & a Soul.

2. That Energy, call'd Evil, is alone from the Body; & that Reason, call'd Good, is alone from the Soul.

3. That God will torment Man in Eternity for following his Energies.

But the following contraries to these are True: 1. Man has no Body distinct from his Soul; for that call'd Body is a portion of Soul discern'd by the five Senses, the chief inlets of Soul in this age.

2. Energy is the only life, and is from the Body; and Reason is the bound or outward circumference of Energy.

3. Energy is Eternal Delight."

So ends Guy Brown's comprehensive romp through the scientific world of energy and its more-than-glancing overlap with the world of life. By the time we get there we have gained a new appreciation for the truth burning bright in that artistic mystic's words. In a contemporary science writing scene too often marred by outsized egos windmilling hubris-ridden topics, on the one hand, and journalistic accounts of the quotidian, if irrelevant, habits of famous scientists, on the other, Brown's book is a breath of fresh air. We get not only a slew of fresh-cut facts thoughtfully and provocatively arranged, but a historical and philosophical background and, what is more, a touch of humility. Brown taught bio-energetics, the science of body energy, at Cambridge University for many years before, he says, he realised that he did not himself understand what energy was. Lest you think him an imbecile to write a book on a topic about which he knows nothing, he quickly quotes Nobel-winning physicist Richard Feynman who remarked that "in physics today, we have no knowledge of what energy is... It is an abstract thing." But Brown does know this abstract thing about as well as anyone can, from a multitude of angles both technical and popular. He compares energy to money: it becomes a symbol, a representation rather than an absolute. Unlike, say, paper money, however, which can vanish if a flame is touched to it (itself an energetic transformation), the first law of thermodynamics assures that energy can never disappear. And the second law of thermodynamics condemns this abstract thing to an inevitable loss of quality. Energy, Brown concludes after his historical, professional and philosophical survey, is not a thing so much as the capacity for "movement or change in physical or biological systems". Like money, it can purchase something else, change forms from chemical change to movement to heat; in the cell, from electron electricity generated by the burning of food within the mitochondrial membranes, to proton electricity loading the energy molecule ATP with phosphate electricity, to sodium electricity pushing other chemicals outside cells, including the brain cells you use in comprehending this sentence. "Energy is not in addition to the things themselves: it is rather as if an accountant were examining the situation, assessing the capacity for movement or change."

Despite its fondness for many exciting scientific details, much of it fresh off the press, Brown's book is highly accessible. In "Origins" he gives a cross-cultural overview, from the pneuma of Greece and the chi of the Chinese to the prana of yogis and more recent alchemical and Freudian conceptions of vital force and libido or sex energy. In "The story of living energy" he takes us on a philosophical tour, teasing out the derivation of scientific energy from its western philosophical forerunners. "The machinery of life" takes us on a tour of the cell by blowing it up 100 million times, so that small molecules such as sugars, amino acids and ATP are the size of "apples, cups, and light bulbs". Proteins here are the size of children or small robots, the cell itself is city-sized, but as "there is effectively no gravity inside a cell, let's locate this city out in space, its inhabitants floating around inside". Such picturesque, direct and imaginative writing is typical of Brown's book; in the chapter "The body electric", after relating the latest on cytochrome oxidase, proton pumps and how, driven by proton electricity, ATP spins into existence, Brown concludes that the early 19th-century notion of Frankenstein's monster, "a creature constructed from several bodies and brought to life with electricity", as well as more recent notions of robots and then half-human, half-machine cyborgs, are more than science fiction. "[I]t turns out that we were electrical machines all along." Plugged, we might add, via a nutritional chain, into the sun.

Brown does not stop here: in chapters such as "The pace of life and death", "Getting fat and staying thin", "Brain energy" and "Sex and sleep", he veers increasingly towards the human and personal realm. At this point it becomes a kind of self-help book, but since it is so firmly based on science, rather than the wishful thinking and idiosyncratic programmes for personal change more typical of the genre, we can trust it. Diabetes, appetite, genetics, carbohydrate loading, internal and external energy drugs and the dual modes of energy use of brain and body are among the many topics examined. The evolutionary, physiological and cell biological backdrops of our relationship to energy are always present in Brown's analyses. Again, this makes these analyses much stronger and more intellectually balanced than we are used to finding in popular works devoted to health, energy attainment or brain science. Perhaps Brown's most applicable lesson is the importance of exercise. Nothing is as important to health, or (paradoxically) as energising, as exercise - which, especially if done in short bursts, will actually increase the number of oxygen-using mitochondria, the "energy factories" outside the nucleus in your cells. The body is indeed a complicated "machine", one which strengthens with use. Read this book and, with Brown and Blake, be energised.

Dorion Sagan is a science writer and Lynn Margulis is professor in the department of geosciences, University of Massachusetts, Amherst, United States.