“To Leonardo a landscape, like a human being, was part of a vast machine, to be understood part by part and, if possible, in the whole. Rocks were not simply decorative silhouettes. They were part of the earth's bones, with an anatomy of their own, caused by some remote seismic upheaval. Clouds were not random curls of the brush, drawn by some celestial artist, but were the congregation of tiny drops formed from the evaporation of the sea, and soon would pour back their rain into the rivers.”

“Were I a nightingale, I would act the part of a nightingale; were I a swan, the part of a swan.”

“Nature is part our humanity, and without some awareness and experience of that divine mystery man ceases to be man. When the Pleiades and the wind in the grass are no longer a part of the human spirit, a part of very flesh and bone, man becomes, as it were, a kind of cosmic outlaw, having neither the completeness and integrity of the animal nor the birthright of a true humanity.”

“The American settlers came to take and shape the land. The first occupants of the land — the "Indians" whom the European migrants encountered — would not be treated, in the pattern of the Romans, as people to be incorporated into an empire. Instead, they were treated as part of the landscape. Most of them were simply cleared away, like the forest, or pushed back, like the wilderness.”

“If the moon and earth were not retained in their orbits by their animal force or some other equivalent, the earth would mount to the moon by a fifty-fourth part of their distance, and the moon fall towards the earth through the other fifty-three parts, and they would there meet, assuming, however, that the substance of both is of the same density.”

“I understood that some parts were still a little sketchy and I wanted some more time to think about whether or not this was really appropriate to release to the Harvard community.”

“The totality is not, as it were, a mere heap, but the whole is something besides the parts.”

“No matter who you are, there is some part of you that always wishes you were someone else.”

“Gargoyles were the complement to saints; Leonardo's caricatures were complementary to his untiring search for ideal beauty. And gargoyles were the expression of all the passions, the animal forces, the Caliban gruntings and groanings which are left in human nature when the divine has been poured away. Leonardo was less concerned than his Gothic predecessors with the ethereal parts of our nature, and so his caricatures, in their expression of passionate energy, merge imperceptibly into the heroic.”

“There was a time when a fool and his money were soon parted, but now it happens to everybody.”