Excerpt from Leonardo da Vinci by Walter Isaacson, plus links to reviews, author biography & more

The whale fossil triggered a dark vision of what would be, throughout his life, one of his deepest forebodings, that of an apocalyptic deluge. On the next side of the sheet he described at length the furious power once held by the long-dead whale: "You lashed with swift, branching fins and forked tail, creating in the sea sudden tempests that buffeted and submerged ships." Then he turned philosophical. "Oh time, swift despoiler of all things, how many kings, how many nations hast thou undone, and how many changes of states and of circumstances have happened since this wondrous fish perished."

By this point Leonardo's fears were about a realm far different from whatever dangers might be lurking inside the cave. Instead they were driven by an existential dread in the face of the destructive powers of nature. He began scribbling rapidly, using a silverpoint on a red-tinted page, describing an apocalypse that begins with water and ends with fire. "The rivers will be deprived of their waters, the earth will no longer put forth her greenery; the fields will no more be decked with waving corn; all the animals, finding no fresh grass for pasture, will die," he wrote. "In this way the fertile and fruitful earth will be forced to end with the element of fire; and then its surface will be left burnt up to cinder and this will be the end of all earthly nature."

The dark cave that Leonardo's curiosity compelled him to enter offered up both scientific discoveries and imaginative fantasies, strands that would be interwoven throughout his life. He would weather storms, literally and psychologically, and he would encounter dark recesses of the earth and soul. But his curiosity about nature would always impel him to explore more. Both his fascinations and his forebodings would be expressed in his art, beginning with his depiction of Saint Jerome agonizing near the mouth of a cave and culminating in his drawings and writings about an apocalyptic deluge.

Leonardo da Vinci is sometimes incorrectly called "da Vinci," as if that were his last name rather than a descriptor meaning "from Vinci." However, the usage is not as egregious as some purists proclaim. During Leonardo's lifetime, Italians increasingly began to regularize and register the use of hereditary surnames, and many of these, such as Genovese and DiCaprio, derived from family hometowns. Both Leonardo and his father, Piero, frequently appended "da Vinci" to their names. When Leonardo moved to Milan, his friend the court poet Bernardo Bellincioni referred to him in writing as "Leonardo Vinci, the Florentine."

Excerpted from Leonardo da Vinci by Walter Isaacson. Copyright © 2017 by Walter Isaacson. Excerpted by permission of Simon & Schuster. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.