There are plenty of awesome, new science books to keep geeks happy this Christmas. But one anonymous science-lover recently received the ultimate stocking stuffer—Laura Geggel at LiveScience reports that the most expensive printed science book was recently sold at Christie's in New York. An anonymous buyer purchased a rare first edition of Sir Isaac Newton’s Philosophiæ Naturalis Principia Mathematica for $3.7 million.

According to Jasper Jackson at The Guardian, the auction house believed the book would sell for $1 to $1.5 million. The most recent sale surpasses an English-language edition of the Principia which was presented to King James II which sold in 2013 for $2.5 million.

If there’s any science book that deserves to set a sales record, it’s the Principia. Published in 1687, the book sets out for the first time Newton’s three laws of motion, which shaped the course of modern physics. Geggel reports that Einstein called the book “perhaps the greatest intellectual stride that it has ever been granted to any man to make.”

Keith Moore, the head of the Royal Society Library, tells Jackson he agrees with that assessment. “It’s not just the history and development of science; it’s one of the greatest books ever published,” he says. “It was hugely influential in terms of applying mathematics to basic physical problems.”

Rawlinson reports that this particular edition was part of set of books designed to be sold in mainland Europe, instead of in Great Britain. It was one of an estimated 80 goatskin-clad Continental editions produced. Geggel points out that the book owes its existence to another eminent scientist, Edmund Halley of comet fame. Though the Royal Society had agreed to print Newton’s masterpiece, they had just blown all their money on an exhaustive book on the history of fish. Halley believed Newton’s book was so important that he stepped in and paid for the printing at his own expense, reports Geggel.

So who was willing to pony up almost $4 million for a 9-inch by 7-inch book? The winner was anonymous, but Moore says as science and tech continues to mint more millionaires, interest and reverence for the artifacts and history of science are growing too. “People who have big books these days maybe are the kinds of people who have made their money on the internet or the web ... If you have a few million quid to spend, why wouldn’t you buy a copy of Principia Mathematica?” he tells Jackson. “If you’ve made your money from a really cool algorithm, you will probably appreciate Newtonian physics.”

Despite its importance and impressive price, the Principia doesn’t come anywhere close to the most expensive printed book ever sold. That honor goes to a religious text, The 1640 Bay Psalm Book, believed to be the first book printed in Colonial America. That tome sold at auction in 2013 for $14.2 million, reports Michael Muskal at The L.A. Times.