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French President Receives Bill Gates at ELysee Palace in Paris
Chesnot—Getty Images

Yesterday, Bill Gates gave a graduation speech — via Twitter.

And the richest man in the world has helped propel a psychology book to the penultimate spot on the Amazon best-seller list using just 140 characters.

First published in 2012, The Better Angels of Our Nature: Why Violence Has Declined, by Harvard psychologist Steven A. Pinker, argues violence has actually been decreasing in recent centuries, and attempts to explain what may be driving this phenomenon. Mark Zuckerberg previously named it as a "book of the year" pick.

As the Washington Post first noted, as of Tuesday morning, since Gates' Tweet, the book has climbed 608,850 percent to move to No. 2 on the overall Amazon best-seller book list, just behind perennial graduation-time best-seller, Oh, The Place You'll Go!, by Dr. Seuss.

Here's what Gates had to say about "Angels":

You can buy Pinker's book at Amazon. Here's Gates' full Tweet-speech:

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