The year was 1995. The venture capitalist Ben Horowitz, who recently made news by endorsing Donald Trump for president, was in his late twenties, working as a computer engineer for a software company in Silicon Valley. He was good at his job, but not obviously headed for great things. Marc Andreessen, on the other hand, was a legend in the making. He was only twenty-two, but had already co-founded Netscape Communications, the world’s first great web browser company. Andreessen had co-written the code for the first iteration of the browser, Mosaic, when still an undergraduate computer science major at the…