Why did Leonardo's brilliant notebooks stay out of science for so long?

Mostly because he never published them, and then the papers were scattered. Leonardo da Vinci filled about 13,000 pages with notes and drawings that fuse art and natural philosophy, from grocery lists to designs for wings and shoes for walking on water. Most are in mirror-image cursive, and since he wrote with his left hand, right to left was probably easier. He said in his notes that he intended to prepare them for publication, but why he never did is unknown.

After he died, the loose notebooks were largely entrusted to his pupil and heir Francesco Melzi, to be published, a task of overwhelming difficulty because of its scope and Leonardo's idiosyncratic writing. After Melzi's death in 1570 his son Orazio took little interest. The sculptor Pompeo Leoni gathered the Codex Atlanticus by dismembering some of the notebooks, and in 1796 Napoleon seized about a dozen of the manuscripts and sent them to Paris.

The cost showed up in science. Leonardo stated the laws of sliding friction in 1493, but his results were never published, and the laws were rediscovered only in 1699 by Guillaume Amontons, whose name they usually carry. He made more than 240 anatomical drawings and wrote about 13,000 words toward an anatomy treatise, yet only a little of it reached print in the Treatise on Painting, first published in 1651.

Today the notebooks can be read. In the Codex Leicester Leonardo explained why sea fossils turn up on mountains, and why the dark part of a crescent Moon glows faintly. Bill Gates bought that codex in 1994 for US$30,802,500.