Fritjof Capra Read Free Page B

Leonardo’s drawings—as art and as tools of scientific analysis—shows us why his science cannot be understood without his art, nor his art without his science. His assertion that “painting embraces in itself all the forms of nature” cuts both ways. In order to practice his art, he needed the scientific understanding of the forms of nature; in order to analyze the forms of nature, he needed the artistic ability to draw them.
    In addition to his keen intellect and powers of observation, his experimental ingenuity, and his great artistic talents, Leonardo also had a very practical bent. As he pursued his investigations of nature’s forms, beholding them with the eye of a scientist and painter, the useful applications of his discoveries were never far from his mind. He spent a major part of his life conceiving machines of all kinds, inventing numerous mechanical and optical devices, and designing buildings, gardens, and cities.
    When he studied water, he saw it not only as the medium of life and the driving force of nature, but also as a source of power for industrial systems, similar to the role that steam—another form of water—would play in the Industrial Revolution three centuries later. His extensive investigations of the flows of air and wind and the flight of birds led him to invent various flying machines, many of them based on sound aerodynamic principles. Indeed, Leonardo’s achievements as a designer and engineer are on a par with his accomplishments as an artist and scientist.
    THE EYE AND THE APPEARANCE OF FORMS
    In his
Treatise on Painting
, Leonardo makes clear that painting is the unifying perspective and integrating thread that runs through all his fields of study. From this work, a coherent conceptual structure emerges, which he might have intended to use for the eventual publications of his Notebooks.
    Like all true scientists, Leonardo based his science on systematic observation. Hence his starting point is the human eye. His careful investigations of the anatomy of the eye and the origin of vision were unparalleled in his time. He paid particular attention to the connections between the eye and the brain, which he demonstrated in a series of beautiful drawings of the human skull. Using brilliant anatomical dissections, Leonardo displayed for the first time the complete path of vision through the pupil and lens to the optic nerve, and all the way to a specific cavity in the brain, known to neurologists today as the third cerebral ventricle. 12
    This is where he located the “seat of the soul,” where all sense impressions meet. Leonardo’s concept of the soul comes very close to what cognitive scientists today call “cognition,” the process of knowing. 13 His theory of how sensory impulses travel along the nerves from the sense organs to the brain is so ingenious that I doubt if neuroscientists today could conceive of anything better, were they given the restrictions of having to work without any knowledge of electromagnetism, biochemistry, and microbiology.
    Leonardo saw his discoveries in optics and the physiology of vision as the grounding of his science of painting, beginning with the science of perspective, the outstanding innovation of Renaissance art. “Painting is based on perspective,” he explains, “and perspective is nothing else than a thorough knowledge of the function of the eye.” 14 From perspective, he moved on to explore the geometry of light rays (known today as geometrical optics), the effects of light falling on spheres and cylinders, the nature of shadow and of contrasts, and the juxtaposition of colors.
    These systematic studies, illustrated in long series of intricate drawings, were the scientific basis of Leonardo’s extraordinary artistic ability to understand and render the most subtle visual complexities. Most renowned was his invention and mastery of a special art of shading—a melting of shades, known as sfumato—which delicately blurs the outlines of