Bill Gates isn't known to be a frivolous spender. He (along with Warren Buffett and a handful of other billionaires) has promised to give away most of his fortune to philanthropic causes, drives a Tesla (quite modest, considering how expensive cars can get), doesn't like to buy pricey clothes and can be seen quietly waiting in line for a burger at the same Seattle drive-in he's been going to for years.
Despite all that, in 1994, right before he first became the richest person in the world, Gates couldn't resist splurging on Leonardo da Vinci's "Codex Leicester" for $30.8 million — making it one of the most expensive books ever sold. The 72-page document, which contains Leonardo's sketches and ideas about subjects like astronomy, mechanics, botany, mathematics and architecture, was written between 1506 and 1510.
By understanding the reasons Gates bought the notebook, we can learn a lot about the importance of obsessing over the heroes that inspire us most: