LEONARDO'S MIRROR: REFLECTIONS ON THE EMERGENCE OF GEOLOGY AND EVOLUTIONARY THOUGHT DURING THE RENAISSANCE , THE SCIENTIFIC REVOLUTION, AND THE ENLIGHTENMENT

In Leonardo da Vinci's drawing (ca. 1487), “Allegory of the Mirror” a Florentine man sits on a rock and with a mirror reflects the rays of the sun at a menagerie of real and imaginary animals romping in a canyon with stratified walls. Like his contemporaries, Leonardo's understanding of the geometry of light helped illuminate the anatomy of living things and of the landscape in a revolutionary way. This led to momentous changes in Western civilization, not least of which occurred during the Scientific Revolution and the Enlightenment. Optics, astronomy, and anatomy were among the first sciences founded, and geology and evolutionary biology were among the last. Nevertheless, even before Steno and Darwin nailed their “golden spikes” to mark the start of the modern understanding of evolution of the Earth and life, artists had established an aesthetic tradition based on geometry that addressed issues of the structure, processes, transformations, and laws of nature and which facilitated the later development of the evolutionary sciences. In fact, there is new evidence that Steno was aware of this artistic tradition.

Art history spanning the Renaissance to the Enlightenment (and beyond) records a growing interest in the structure of the Earth, soils, erosion, earthquakes, floods, river flow, evolution, etc. Notable contributions come from 15th-16th Cy artists such as di Giorgio, Leonardo, Galileo, and Dürer and 17th Cy artists such as Rubens, van Goyen, and Ruisdael. Even the 19th Cy (Romantic) works of Ruskin and Turner are consonant with emergence of an evolutionary perspective of nature—despite Ruskin's hostility towards Darwin's ideas. Thomas Jefferson's coordinate surveys of America are the outgrowth and American epitome of the geometric study of the landscape. Early on, geometry standardized the description of nature and provided the means of depicting it to scale which, as Edgerton has stated, contributed to the development of democracy for such works communicate the same information to anyone with a modest education. Later, geometric transformations of space made it possible to visualize evolution. Thus, the origin of evolutionary science is, like all of the other sciences, integral to the development of democracy, which we celebrate here in Philadelphia, the epicenter of the American Experiment.