Soliciting upvotes is against the rules and is the definition of a voting ring (https://news.ycombinator.com/newsfaq.html). The idea of HN is that users vote for things they find intellectually interesting, not because they or someone they like are promoting something. If we didn't have such a rule, as well as software to enforce it, HN would be overrun by gaming of the voting system. Dozens of posts try to do so every day.

That said, we routinely override the ring detector when the post is good original work, which this obviously is. But we don't do that more than once per project. The trouble here is that from an HN front page point of view, these are all effectively the same story:

https://news.ycombinator.com/item?id=8460670 (the current post)

https://news.ycombinator.com/item?id=8308320

https://news.ycombinator.com/item?id=8263611

https://news.ycombinator.com/item?id=8259528

https://news.ycombinator.com/item?id=8238823

Of course, to someone immersed in hard work on a big project, those are all very different milestones, each worthy of a post. But from an HN point of view, this project has appeared on the front page a lot lately. At least two of those posts got significant attention within the last couple months. That's a lot—already more than pretty much anyone else gets. So I don't see how we can justify overriding the ring detector in the present case without being unfair to everyone else to whom these rules apply. (It goes without saying that none of the above is meant to impugn the quality of the book, which I don't doubt deserves the enthusiasm of its fans.)

Edit: We restored the post because mhartl explained in an email that he didn't know the rules, and I believe him. I'll leave the above comment in the hope that it makes things clearer for everybody, or at least somebody.