The inspiring lesson in creativity packed into 7,200 pages of Leonardo da Vinci’s notebooks

When I embarked on my recently published biography of Leonardo, my starting point was not his art masterpieces. Instead, I based my book on the amazing trove of notebooks that he produced, which can now be found in archives in Florence, Milan, Venice, Madrid, Paris, London, Windsor Castle, and Bill Gates’s home near Seattle. Leonardo’s relentlessly curious and observant mind is revealed, I think, in the more than 7,200 pages of his notes that, miraculously, survive to this day. Paper turns out to be a superb information storage technology, still readable after five hundred years.

As the offspring of a long line of notaries, Leonardo had an instinct for keeping records. Throughout his life, he jotted down observations, to-do lists, ideas, drawings, and writings. The jam-packed pages include ingenious mechanisms he encountered or imagined, notes for books he planned to write, preparatory drawings for his paintings, contrivances for moving theatrical scenery, records of expenses, and sketches of people who caught his imagination.

Fortunately, Leonardo could not afford to waste paper, so he crammed every inch of his pages with entries that seem random but provide intimations of his mental leaps. Scribbled alongside of each other, with rhyme if not reason, are math calculations, sketches of his devilish young boyfriend, birds, flying machines, theater props, eddies of water, blood valves, grotesque heads, angels, siphons, plant stems, sawed-apart skulls, tips for painters, notes on the eye and optics, weapons of war, fables, riddles, and studies for paintings. The cross-disciplinary brilliance whirls across every page, providing a delightful display of a mind dancing with nature. His notebooks are the greatest record of curiosity ever created.

My favorite gems are his to-do lists. One of them, dating from the 1490s in Milan, is that day’s list of things he wants to learn. “The measurement of Milan and its suburbs,” reads the first entry. This has a practical purpose, as revealed by an item later in the list: “Draw Milan.” Others show him relentlessly seeking out people whose brains he could pick: “Get the master of arithmetic to show you how to square a triangle… Ask Giannino the Bombardier about how the tower of Ferrara is walled… Ask Benedetto Protinari by what means they walk on ice in Flanders... Get a master of hydraulics to tell you how to repair a lock, canal and mill in the Lombard manner… Get the measurement of the sun promised me by Maestro Giovanni Francese, the Frenchman.”  He is insatiable.

Over and over again, year after year, Leonardo lists things he must learn. Some involve the type of close observation most of us rarely pause to do. “Observe the goose’s foot: if it were always open or always closed the creature would not be able to make any kind of movement.” Others involve why-is-the-sky-blue questions about phenomena so commonplace that we rarely pause to wonder about them. “Why is the fish in the water swifter than the bird in the air when it ought to be the contrary since the water is heavier and thicker than the air?”

Best of all are the questions that seem completely random. “Describe the tongue of the woodpecker,” he instructs himself.  Who on earth would decide one day, for no apparent reason, that he wanted to know what the tongue of a woodpecker looked like? How would you even find out? It’s not something that Leonardo needed to paint a picture or even to understand the flight of birds. When I first saw his entries about the woodpecker, I regarded it, as most scholars have, as an entertaining oddity – an amuse-bouche, so to speak – that showed the eccentric nature of Leonardo’s relentless curiosity. That it indeed does. But there is more, as I discovered after pushing myself to be more like Leonardo and drill down into random curiosities. Leonardo had become fascinated by the muscles of the tongue. All of the other muscles he studied acted by pulling rather than pushing a body part, but the tongue seemed to be an exception. This was true in humans and also in animals. The most notable example was the tongue of the woodpecker. Nobody had drawn or fully written about it before, but Leonardo with his acute power to observe objects in motion knew that there was something to be learned from it.

Oddest of all, there is this entry: “Go every Saturday to the hot bath where you will see naked men.”  We can imagine Leonardo wanting to do that, for reasons both anatomical and aesthetic. But did he really need to remind himself to do it? The next item on the list is, “Inflate the lungs of a pig and observe whether they increase in width and in length, or only in width.” As the New Yorker art critic Adam Gopnik once wrote, “Leonardo remains weird, matchlessly weird, and nothing to be done about it.”

Not only did Leonardo’s notebooks reveal to me the wondrous nature of his mind, they taught me a lesson: Take notes. Five hundred years later, his notebooks are around to astonish and inspire us. Fifty years from now, our own notebooks, if we work up the initiative to start writing them, will be around to astonish and inspire our grandchildren.

Walter Isaacson is the author of Leonardo da Vinci, on which this article based.