King Francis I, who was at St. Germain-en-Laye with his court, wept when the news was brought to him. Francesco de’ Melzi was so overcome with grief that he waited until June before writing to the half-brothers of Leonardo of the Master’s death. He wrote, in part, “He was to me the best of fathers, and it is impossible for me to express the grief that his death has caused me. Until the day when my body is laid under the ground, I shall experience perpetual sorrow, and not without reason, for he daily showed me the most devoted and warmest affection.” And in a closing paragraph Francesco added these words: “His loss is a grief to everyone, for it is not in the power of nature to reproduce another such man.” 14 _Mankind’s Debt to Leonardo_ When Leonardo died his notebooks began their separate journeys into obscurity. They traveled to different lands and became parts of widely disparate collections. It has only been within the last fifty years that efforts were made to bring them all together between the covers of one volume—a dream that Leonardo himself entertained but never realized. As the manuscripts and drawings were brought to light, translated and published, the extraordinary scope of Leonardo’s scientific explorations was revealed. Mathematician, anatomist, botanist, astronomer and geologist form only part of the long list of his accomplishments and give the clue to the man who considered all the natural world within his province of study. Because of the universality of Leonardo’s scientific thought he has been frequently mentioned as the forerunner of such men as Galileo Galilei, Sir Isaac Newton, James Watt, Francis Bacon and William Harvey. Although Leonardo cannot be credited with the actual discoveries that these men made, his methods of investigation pointed the way down the paths that they would follow. The key to Leonardo’s methods lies in a quotation from his notes on vision. He wrote of vision as _saper vedere_—“to know how to see”—and he referred to the eye as “the window of the soul.” Again and again, he stressed the importance of observation and personal experience. Although he himself was well read, he emphasized that “science comes by observation not by authority.” His supreme talent for drawing underlines his credo and is inseparable from his science. What he saw in the natural world about him needed investigating. The results of these investigations were transformed into drawings as the most certain method for passing this knowledge along to others. The best example of this attitude is represented by his anatomical studies. To merely draw the living figure in front of him was not sufficient—it was imperative to know what he was drawing. He turned to the dissecting room and after intensive study produced some of the finest anatomical drawings in the world—and among the easiest for others to understand.