Editor's note : The following excerpt is from Mastering The VC Game , a new book by Jeffrey Bussgang that goes on sale Thursday. It tells the backstory of Twitter from the perspective of founder Jack Dorsey , from his early obsession with couriers and his attempts to create a better dispatch system to his "Aha" moment with Twitter ("What if we simply set status, archive it on the Web, use SMS to do it, and it all happens in real time?") to why the company picked Fred Wilson of Union Square Ventures as its first venture investor ("I want a VC who is always thinking a few steps ahead of me"). Bussgang interviewed both men, and details how the VC and entrepreneur clicked in the second half of this excerpt. The first part recounts the tale of how Dorsey came to invent Twitter. Jack Dorsey (a.k.a. @jack in the lingo of the Twitterverse) founded Twitter, the social networking and microblogging site where users—Twitterers—post very short (140 characters, tops) updates known as tweets. The concept for Twitter came out of Jack’s lifelong fascination with mapping the real-time movements of people and things within complex environments. “Since I was very small, I’ve been fascinated by how cities work,” Jack told me in his typically straightforward way. “I always got really excited when I thought about visualizing them, specifically around maps. What would you place on a map to show how a city worked?”