Yesterday, Bill Gates gave some very profound advice to graduates in a series of 15 tweets. And while his advice ranged from promising career fields (artificial intelligence, energy, and biosciences) to social (start fighting inequity sooner, whether down the street or around the world) to the people to surround yourself with (people who challenge you, teach you, and push you to be your best self), what most caught my eye was the gift that Bill Gates wishes he could give to every graduate: a book.

This book,The Better Angels of Our Nature, by Harvard psychology professor Steven Pinker, is according to Gates, "the most inspiring book I've ever read."

The book asks the question, are people fundamentally good or are they fundamentally bad? According to Pinker, despite the media's preoccupation with war, crime, terrorism, and violence, research shows that all have been in decline over a long period of time. Instead of a world that is getting worse, we actually live in a world that is getting better. As a result, we should be hopeful for the future, instead of hopeless about it.

Perhaps it's no surprise that, after Gates sent out his series of tweets, The Better Angels of Our Nature has surged on Amazon -- jumping into the No. 2 spot in sales of all books on the site.

So, if you want a dose of inspiration -- and hope for the future of our world -- then consider following Bill Gates's advice. Inspiration is always a good thing, both in business and in life.

Be sure to check out Steven Pinker's TED Talk on the topic in the video below.