LEARNING FROM LEONARDO

This beautifully written and presented book is the sequel to The Science of Leonardo, published in 2007. Fritjof has steeped himself in the notebooks of Leonardo for the last few years, and the result is a fascinating synthesis of his scientific work. The first book provided an introduction to his life, personality and scientific method, while this book contains more in-depth discussion of the main branches of his scientific work in the light of 21st-century systems science, including fluid dynamics, geology, botany, mechanics, science of flight and anatomy. Many of these discoveries are virtually unknown to the general public, as Fritjof observes, and he provides an amazing chart detailing some forty inventions and the era when they were subsequently rediscovered, sometimes not until the 20th century. He also surmises that, if these notebooks had been published sooner, Leonardo might have been acknowledged as the inventor of modern science. What is of particular interest is the way that he connects insights across different disciplines – for instance from the flow of water to sap rising in plants and air moving over a bird's wing - which is the hallmark of a systems thinker. Leonardo was also fundamentally concerned to understand the nature of life and its processes, which he brilliantly conveys in his drawings. Fritjof contrasts science of living forms concerned with movement, change and transformation with the mechanical outlook of Galileo, Descartes and Newton.

At the beginning of the book, Fritjof discusses the nature of Leonardo's genius, commenting that the principal signs are 'his relentless curiosity, intellectual fearlessness, capacity for intense concentration, attention to detail, holistic memory, commitments to the empirical method, and pervasive systemic thinking.' He is always on the lookout for the pattern that connects. The main parts of the book cover form and transformation in the macrocosm, dealing with water, the living Earth and the growth of plants, followed by and transformation in the human body, which begins with the human figure, and moving on to mechanics, dynamics, flight and of life. His insights into the nature of fluid flow create a new branch of science and he correctly describes how vortices are formed. He also understood the fundamental nature of the spiral. Very unusually, he was aware of the length of geological time, not generally accepted until the 19th century, and he works his knowledge of geology into some of his most famous paintings such as the Virgin of the Rocks. He also demonstrated that marine fossils found in mountain rocks had been formed in oceanic environments where these organisms had lived in the distant past. His dynamic approach to plant growth resembles that of Goethe and is again profusely illustrated – Goethe also recommended drawing plants as a means of understanding their processes. He was also the first to realise the correspondence between the rings on a tree and its age while also arriving at a qualitative understanding of branching patterns, secondary growth, phototropism and the responses of trees to injury (p. 124).

The reader benefits enormously from Fritjof's extensive knowledge of the history of science and his own understanding as a systems thinker. Moving on now to the human body, it is fascinating to learn how crude were contemporary anatomical drawings and the enormous improvements made by Leonardo. Again, we have drawings of the hand, arms and leg muscles adding to extensive analysis, while not neglecting the importance of beauty and proportion. Fritjof questions the mechanistic interpretation of Leonardo's work on mechanics and details many of his practical and engineering inventions. He covers the science of weights, fluids in equilibrium, forces and motion, the conservation of energy and Leonardo's work on falling bodies and ballistic trajectories. Here he demonstrates an extraordinary level of abstract thinking that make many of his scientific statements sound modern, even though his science was still rooted in Aristotle. We can also still admire the accuracy and beauty of his many anatomical drawings.

Although his work on the science of flight is predicated on the movement of birds, he still arrived at some new insights in the field, for instance that the compression of air under a bird's wing is critical to the generation of lift - Leonardo was in fact the first person to understand the mechanics of bird flight. Fritjof explains all this in great detail along with his various inventions. Another special area of study was the human heart, where Leonardo understood the function of the valves, but failed to arrive at the circulation of blood, which had to wait another hundred years for William Harvey. He was also the first to understand the nature of atherosclerosis through the dissection of the body of an old man and comparing it with veins from younger people. At the same time, he was able to describe cirrhosis of the liver and was the first to use the term capillary vessels. He also made quantitative observations of fetal growth, which had to wait until the 19th century for further progress.

In his coda, Fritjof suggests that Leonardo's greatest legacy may be his systemic thinking along with his deep respect for nature and life. He believes that our great challenge is to build and nurture sustainable communities and that we can draw inspiration from the genius of Leonardo in acquiring ecoliteracy and redesigning our technologies and institutions. This brilliant book situates Leonardo not only in the history of science but also as the originator of systemic thinking so urgently required in responding to the complex challenges of our time. I am sure that other readers will be similarly astonished at the breadth and depth of Leonardo's thinking and the beauty of his drawings and designs illustrated in this book.